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 A366904 #7 Oct 28 2023 03:47:30
%S A366904 1,1,1,1,1,1,1,9,1,1,1,1,1,1,1,9,1,1,1,1,1,1,1,9,1,1,28,1,1,1,1,41,1,
%T A366904 1,1,1,1,1,1,9,1,1,1,1,1,1,1,9,1,1,1,1,1,28,1,9,1,1,1,1,1,1,1,105,1,1,
%U A366904 1,1,1,1,1,9,1,1,1,1,1,1,1,9,28,1,1,1,1
%N A366904 The sum of exponentially evil divisors of n.
%C A366904 The number of these divisors is A366902(n) and the largest of them is A366906(n).
%H A366904 Amiram Eldar, <a href="/A366904/b366904.txt">Table of n, a(n) for n = 1..10000</a>
%F A366904 Multiplicative with a(p^e) = 1 + Sum_{k = 1..e, k is evil} p^k.
%F A366904 a(n) >= 1, with equality if and only if n is a cubefree number (A004709).
%t A366904 f[p_, e_] := 1 + Total[p^Select[Range[e], EvenQ[DigitCount[#, 2, 1]] &]]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100]
%o A366904 (PARI) a(n) = {my(f = factor(n)); prod(i = 1, #f~, 1 + sum(k = 1, f[i, 2], !(hammingweight(k)%2) * f[i, 1]^k));}
%Y A366904 Cf. A004709, A366902, A366906.
%Y A366904 Similar sequences: A353900, A365682, A366903.
%K A366904 nonn,easy,mult
%O A366904 1,8
%A A366904 _Amiram Eldar_, Oct 27 2023