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 A378437 #7 Nov 26 2024 20:59:34
%S A378437 1,-1,-1,0,-1,0,-1,0,0,1,-1,0,-1,1,1,0,-1,0,-1,-1,1,1,-1,-2,0,1,0,-1,
%T A378437 -1,-2,-1,0,1,1,1,-2,-1,1,1,-1,-1,-1,-1,0,0,1,-1,-2,0,0,1,0,-1,0,1,0,
%U A378437 1,1,-1,-26,-1,1,0,0,1,-1,-1,0,1,-1,-1,-14,-1,1,0,0,1,0,-1,-1,0,1,-1,-19,1,1,1,-1,-1,-17,1,0,1,1,1
%N A378437 Dirichlet inverse of A033630, where A033630 is the number of partitions of n into distinct divisors of n.
%H A378437 Antti Karttunen, <a href="/A378437/b378437.txt">Table of n, a(n) for n = 1..20000</a>
%F A378437 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A033630(n/d) * a(d).
%o A378437 (PARI)
%o A378437 A033630(n) = if(!n, 1, my(p=1); fordiv(n, d, p *= (1 + 'x^d)); polcoeff(p, n));
%o A378437 memoA378437 = Map();
%o A378437 A378437(n) = if(1==n,1,my(v); if(mapisdefined(memoA378437,n,&v), v, v = -sumdiv(n,d,if(d<n,A033630(n/d)*A378437(d),0)); mapput(memoA378437,n,v); (v)));
%Y A378437 Cf. A033630, A378438 (Möbius transform).
%K A378437 sign
%O A378437 1,24
%A A378437 _Antti Karttunen_, Nov 26 2024