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 A100649 #12 Aug 25 2025 10:13:28
%S A100649 1,3,4,4,41,41,47,47,289,289,1502,1502,15551,15551,5809,5809,3818123,
%T A100649 3818123,-76776508,-76776508,934336415,934336415,-127396984577,
%U A100649 -127396984577,6013822435553,6013822435553,-149990624319638,-149990624319638,167911724519886437,167911724519886437
%N A100649 a(n) is the numerator of 1 - Sum_{i=1..n} Bernoulli(i).
%e A100649 1, 3/2, 4/3, 4/3, 41/30, 41/30, 47/35, 47/35, 289/210, 289/210, 1502/1155, 1502/1155, 15551/10010, 15551/10010, 5809/15015, 5809/15015, 3818123/510510, 3818123/510510, ...
%p A100649 A100649 := proc(n) 1-add( bernoulli(i),i=1..n) ; numer(%) ; end proc: # _R. J. Mathar_, Jul 01 2011
%t A100649 a[n_]:=Numerator[1-Sum[BernoulliB[i],{i,n}]]; Array[a,30,0] (* _Stefano Spezia_, Aug 25 2025 *)
%Y A100649 Cf. A027641, A027642, A100650 (denominators).
%K A100649 sign,frac,changed
%O A100649 0,2
%A A100649 _N. J. A. Sloane_, Dec 05 2004