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 A140219 #22 Nov 29 2022 04:25:54
%S A140219 1,1,2,2,6,6,6,6,10,10,6,6,210,210,2,2,30,30,42,42,110,110,6,6,546,
%T A140219 546,2,2,30,30,462,462,170,170,6,6,51870,51870,2,2,330,330,42,42,46,
%U A140219 46,6,6,6630,6630,22,22,30,30,798,798,290
%N A140219 Denominator of the coefficient [x^1] of the Bernoulli twin number polynomial C(n,x).
%C A140219 See A140351 for the main part of the documentation.
%F A140219 a(n) = denominator(Sum_{i=0..n} binomial(n,i)*(i+1)*bern(i)). - _Vladimir Kruchinin_, Oct 05 2016
%F A140219 a(n) = A006955(floor(n/2)). - _Georg Fischer_, Nov 29 2022
%p A140219 C := proc(n, x) if n = 0 then 1; else add(binomial(n-1, j-1)* bernoulli(j, x), j=1..n) ; expand(%) ; end if ; end proc:
%p A140219 A140219 := proc(n) coeff(C(n, x), x, 1) ; denom(%) ; end proc:
%p A140219 seq(A140219(n), n=1..80) ; # _R. J. Mathar_, Sep 22 2011
%t A140219 Table[Sum[Binomial[n, k]*(k+1)*BernoulliB[k], {k, 0, n}], {n, 0, 60}] // Denominator (* _Vaclav Kotesovec_, Oct 05 2016 *)
%o A140219 (Maxima) makelist(denom(sum((binomial(n, i)*(i+1)*bern(i)), i, 0, n)), n, 0, 20); /* _Vladimir Kruchinin_, Oct 05 2016 */
%o A140219 (PARI) a(n) = denominator(sum(i=0, n, binomial(n,i)*(i+1)*bernfrac(i))); \\ _Michel Marcus_, Oct 05 2016
%Y A140219 Cf. A002427, A006955, A048594, A140351 (numerators).
%K A140219 nonn,frac
%O A140219 0,3
%A A140219 _Paul Curtz_, Jun 23 2008