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 A387725 #11 Sep 06 2025 21:40:37
%S A387725 0,0,0,0,0,1,0,0,0,1,0,1,0,1,1,0,0,1,0,1,1,1,0,1,0,1,0,1,0,4,0,0,0,1,
%T A387725 0,1,0,1,0,1,0,4,0,1,1,1,0,1,0,1,0,1,0,1,0,1,0,1,0,4,0,1,0,0,0,3,0,1,
%U A387725 0,3,0,1,0,1,1,1,0,3,0,1,0,1,0,4,0,1,0,1,0,4,0,1,0,1,0,1,0,1,0,1,0,3,0,1,3
%N A387725 Number of unitary divisors d of n for which A107758(d) > 2*d, where A107758 is sigma+, multiplicative function with a(p^e) = 1+sigma(p^e).
%H A387725 Antti Karttunen, <a href="/A387725/b387725.txt">Table of n, a(n) for n = 1..65537</a>
%F A387725 a(n) = Sum_{d|n} [gcd(d,n/d)==1 and A107758(d) > 2*d], where [ ] is the Iverson bracket.
%o A387725 (PARI)
%o A387725 A107758(n) = { my(f = factor(n)); prod(k=1, #f~, 1+sigma(f[k, 1]^f[k, 2])); };
%o A387725 A387725(n) = sumdiv(n,d,(1==gcd(d,n/d)) && (A107758(d)>(2*d)));
%Y A387725 Cf. A107758, A387721 (positions of positive terms).
%Y A387725 Cf. also A387715, A337345.
%K A387725 nonn,new
%O A387725 1,30
%A A387725 _Antti Karttunen_, Sep 06 2025