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 A213621 #13 Aug 02 2019 11:06:05
%S A213621 1,1,1,1,1,3,1,3,1,5,1,3,1,105,5,3,1,15,5,105,7,165,5,15,1,273,7,7,1,
%T A213621 15,1,231,77,1785,35,3,1,25935,455,105,7,1155,55,1155,7,2415,35,105,1,
%U A213621 3315,221,429,11,165,55,399,19,435,5,15,1,465465,5005,2145
%N A213621 The denominator of the Bernoulli polynomial B(n,x) divided by the Clausen number C(n), A144845(n)/A141056(n).
%p A213621 # Clausen(n,k) defined in A160014.
%p A213621 seq(denom(bernoulli(i,x))/Clausen(i,1), i=0..63);
%t A213621 c[0, _] = 1; c[n_, k_] := Times @@ (Select[Divisors[n], PrimeQ[#+k]&] + k);
%t A213621 Table[Denominator[BernoulliB[i, x] // Together]/c[i, 1], {i, 0, 63}] (* _Jean-François Alcover_, Aug 02 2019 *)
%Y A213621 Cf. A213623.
%K A213621 nonn
%O A213621 0,6
%A A213621 _Peter Luschny_, Jun 16 2012