This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A136686 #33 Feb 16 2025 08:33:07
%S A136686 19,47,164,235,504,1109,1112,5134,9222,12803
%N A136686 Numbers k such that A136677(k) is prime.
%C A136686 A136677(k) = Numerator of Sum_{j=1..k} (-1)^(j+1)/j^6.
%H A136686 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HarmonicNumber.html">Harmonic Number</a>.
%t A136686 Do[ f=Numerator[ Sum[ (-1)^(k+1)*1/k^6, {k,1,n} ] ]; If[ PrimeQ[f], Print[ {n,f} ] ], {n,1,130} ]
%Y A136686 Cf. A058313, A119682, A136675, A120296, A136676, A136677. Cf. A001008, A007406, A007408, A007410, A099828, A103345. Cf. A136681, A136682, A136683, A136684, A136685.
%K A136686 nonn,hard,more
%O A136686 1,1
%A A136686 _Alexander Adamchuk_, Jan 16 2008
%E A136686 a(4)-a(5) from _Hiroaki Yamanouchi_, Sep 22 2014
%E A136686 a(6) from _Amiram Eldar_, Mar 14 2019
%E A136686 a(7)-a(9) from _Robert Price_, Apr 20 2019
%E A136686 a(10) from _Michael S. Branicky_, Nov 16 2024