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 A378440 #8 Nov 27 2024 15:56:47 %S A378440 1,0,0,0,0,-1,0,0,0,0,0,-1,0,0,0,0,0,-1,0,-1,0,0,0,-3,0,0,0,-1,0,-2,0, %T A378440 0,0,0,0,-3,0,0,0,-2,0,-1,0,0,0,0,0,-5,0,0,0,0,0,-1,0,-1,0,0,0,-29,0, %U A378440 0,0,0,0,-1,0,0,0,0,0,-19,0,0,0,0,0,0,0,-3,0,0,0,-21,0,0,0,-1,0,-19,0,0,0,0,0,-11,0,0,0,-1 %N A378440 Dirichlet inverse of Möbius transform of A033630, where A033630 is the number of partitions of n into distinct divisors of n. %C A378440 Equally, inverse Möbius transform of A378437, which is the Dirichlet inverse of A033630. %H A378440 Antti Karttunen, <a href="/A378440/b378440.txt">Table of n, a(n) for n = 1..20000</a> %F A378440 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A378439(n/d) * a(d). %F A378440 a(n) = Sum_{d|n} A378437(d). %o A378440 (PARI) %o A378440 A033630(n) = if(!n, 1, my(p=1); fordiv(n, d, p *= (1 + 'x^d)); polcoeff(p, n)); %o A378440 A378439(n) = sumdiv(n, d, moebius(n/d)*A033630(d)); %o A378440 memoA378440 = Map(); %o A378440 A378440(n) = if(1==n,1,my(v); if(mapisdefined(memoA378440,n,&v), v, v = -sumdiv(n,d,if(d<n,A378439(n/d)*A378440(d),0)); mapput(memoA378440,n,v); (v))); %Y A378440 Inverse Möbius transform of A378437. %Y A378440 Dirichlet inverse of A378439. %Y A378440 Cf. A033630. %K A378440 sign %O A378440 1,24 %A A378440 _Antti Karttunen_, Nov 27 2024