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 A213623 #11 Aug 13 2019 08:13:26
%S A213623 0,1,2,3,4,6,8,10,12,16,24,28,30,36,48,60,120
%N A213623 Numbers n such that the denominator of the Bernoulli polynomial B(n,x) equals the Clausen number C(n), {n | A144845(n) = A141056(n)}.
%C A213623 Is this a finite sequence?
%p A213623 # Clausen(n, k) defined in A160014.
%p A213623 seq(`if`(denom(bernoulli(i,x))=Clausen(i,1),i,NULL), i=0..120);
%t A213623 Clausen[n_, k_] := If[n == 0, 1, Times @@ (Select[Divisors[n], PrimeQ[# + k]&] + k)];
%t A213623 Select[Range[0, 120], Denominator[BernoulliB[#, x] // Together] == Clausen[#, 1]&] (* _Jean-François Alcover_, Aug 13 2019 *)
%Y A213623 Cf. A141056, A144845, A213621.
%K A213623 nonn,more
%O A213623 0,3
%A A213623 _Peter Luschny_, Jun 16 2012