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 A372470 #10 May 04 2024 04:49:28 %S A372470 1,2,2,0,2,4,2,4,0,4,2,0,2,4,4,0,2,0,2,0,4,4,2,8,0,4,4,0,2,8,2,0,4,4, %T A372470 4,0,2,4,4,8,2,8,2,0,0,4,2,0,0,0,4,0,2,8,4,8,4,4,2,0,2,4,0,0,4,8,2,0, %U A372470 4,8,2,0,2,4,0,0,4,8,2,0,0,4,2,0,4,4,4 %N A372470 Multiplicative with a(p^e) = e+1 if e+1 is a power of 2, and 0 otherwise. %H A372470 Amiram Eldar, <a href="/A372470/b372470.txt">Table of n, a(n) for n = 1..10000</a> %F A372470 a(n) = A359473(n)*A000005(n). %F A372470 a(A036537(n)) = A000005(A036537(n)) = A372468(n). %t A372470 f[p_, e_] := If[e + 1 == 2^IntegerExponent[e + 1, 2], e + 1, 0]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] %o A372470 (PARI) a(n) = vecprod(apply(x -> if(x+1 == 1 << valuation(x+1, 2), x+1, 0), factor(n)[, 2])); %Y A372470 Cf. A000005, A036537, A359473, A372468. %K A372470 nonn,easy,mult %O A372470 1,2 %A A372470 _Amiram Eldar_, May 02 2024