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 A335954 #8 Jul 21 2020 11:48:15 %S A335954 1,11,127,221,367,-1895,1447237,-57253,118526399,-5749677193, %T A335954 91546283957,-1792042789427,1982765468376757,-286994504449237, %U A335954 3187598676787485443,-4625594554880206360895,16555640865486520494719,-22142170099387402072693,904185845619475242495903560731 %N A335954 a(n) = Numerator(-2*n*HurwitzZeta(1 - 2*n, -1/2)) for n > 0, and a(0) = 1. %F A335954 a(n) = Numerator(Bernoulli(2*n, -1/2)). %p A335954 a := n -> numer(`if`(n=0, 1, -2*n*Zeta(0, 1-2*n, -1/2))): seq(a(n), n=0..18); %t A335954 a[0] := 1; a[n_] := -2 n HurwitzZeta[1 - 2 n, -1/2]; Array[a, 18, 0] // Numerator %o A335954 (PARI) a(n) = numerator(subst(bernpol(2*n, x), x, -1/2)); \\ _Michel Marcus_, Jul 21 2020 %Y A335954 Cf. A033469 (denominators), A001896 (evaluated at x=+1/2). %K A335954 sign %O A335954 0,2 %A A335954 _Peter Luschny_, Jul 21 2020