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 A250213 #24 Apr 02 2020 04:30:48
%S A250213 0,0,0,0,0,0,0,1,0,1,0,2,1,2,0,2,1,1,1,3,2,2,2,3,2,2,1,2,2,4,2,2,3,3,
%T A250213 1,3,1,3,1,1,2,3,1,3,4,5,2,2,3,1,2,4,4,4,3,4,3,5,4,2,3,3,4,5,2,3,2,4,
%U A250213 5,5,3,3,2,5,1,5,2,4,3,2,5,3,3,2,5,3,3,4
%N A250213 Number of distinct prime factors of A241601(n).
%C A250213 a(n) = 0 iff n is in the set {0, 1, 2, 3, 4, 5, 6, 8, 10, 14};
%C A250213 a(n) = 1 iff n is in A250220.
%F A250213 a(n) = A001221(A241601(n)).
%t A250213 b[n_] := Numerator[BernoulliB[2 n]/(2 n)];
%t A250213 c[n_] := Numerator[SeriesCoefficient[Log[Tan[x]+1/Cos[x]], {x, 0, 2n+1}]];
%t A250213 a[0] = 0; a[n_] := PrimeNu[If[EvenQ[n], Abs[b[n/2]], c[(n-1)/2]]];
%t A250213 Table[a[n], {n, 0, 78}] (* _Jean-François Alcover_, Jul 04 2019 *)
%Y A250213 Cf. A001221, A241601, A249909, A250214, A250220.
%K A250213 nonn
%O A250213 0,12
%A A250213 _Eric Chen_, Dec 28 2014
%E A250213 More terms from _Jean-François Alcover_, Jul 04 2019
%E A250213 More terms from _Jinyuan Wang_, Apr 02 2020