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 A372469 #7 May 02 2024 10:06:31
%S A372469 0,1,1,1,2,1,2,2,1,1,2,2,1,1,2,2,1,3,2,2,1,3,1,2,2,2,1,2,2,3,1,3,1,2,
%T A372469 1,2,1,3,2,3,2,2,1,1,2,2,3,1,2,3,1,1,2,2,3,1,2,1,2,2,2,3,1,2,2,2,2,1,
%U A372469 1,3,1,3,3,2,1,1,3,2,1,3,2,2,2,4,2,2,2
%N A372469 a(n) = log_2(A372468(n)).
%H A372469 Amiram Eldar, <a href="/A372469/b372469.txt">Table of n, a(n) for n = 1..10000</a>
%t A372469 f[n_] := Module[{p = Times @@ (1 + FactorInteger[n][[;; , 2]]), e}, e = IntegerExponent[p, 2]; If[p == 2^e, e, Nothing]]; f[1] = 0; Array[f, 150]
%o A372469 (PARI) lista(kmax) = {my(p, e); for(k = 1, kmax, p = vecprod(apply(x -> x + 1, factor(k)[, 2])); e = valuation(p, 2); if(p >> e == 1, print1(e, ", "))); }
%Y A372469 Cf. A372468.
%K A372469 nonn,easy
%O A372469 1,5
%A A372469 _Amiram Eldar_, May 02 2024