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 A309431 #32 Aug 06 2019 19:29:23
%S A309431 1,1,0,2,5,-2,-6,1,10,7,13,-11,-15,-5,32,0,34,-23,5,30,-66,33,29,-18,
%T A309431 -60,-17,13,69,-21,-65,65,17,8,50,-6,24,-33,-23,130,13,115,-93,184,
%U A309431 -132,4,48,-11,31,70,-99,-23,192,-258,154,-68,155,-18,16,-35,-101,-11
%N A309431 a(n) = Sum_{k=2..p} (-1)^k * A240236(p, k), where p is n-th prime.
%H A309431 Seiichi Manyama, <a href="/A309431/b309431.txt">Table of n, a(n) for n = 1..1000</a>
%F A309431 a(n) = A309531(A000040(n)).
%o A309431 (PARI) {a(n) = sum(k=2, prime(n), (-1)^k*sumdigits(prime(n), k))}
%Y A309431 Cf. A000040, A240236, A309531.
%K A309431 sign,base
%O A309431 1,4
%A A309431 _Seiichi Manyama_, Aug 06 2019