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 A378210 #6 Nov 22 2024 13:31:49
%S A378210 1,-3,-4,-1,-6,5,-8,5,-1,9,-12,22,-14,13,14,7,-18,28,-20,32,20,21,-24,
%T A378210 -1,-1,25,11,42,-30,51,-32,-3,32,33,34,-28,-38,37,38,-9,-42,63,-44,62,
%U A378210 49,45,-48,-76,-1,56,50,72,-54,-6,54,-17,56,57,-60,-182,-62,61,63,-17,64,87,-68,92,68,75,-72,-183,-74,73
%N A378210 Dirichlet inverse of A191150, hypersigma variant 1.
%H A378210 Antti Karttunen, <a href="/A378210/b378210.txt">Table of n, a(n) for n = 1..20000</a>
%F A378210 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A191150(n/d) * a(d).
%o A378210 (PARI)
%o A378210 A191150(n) = (sigma(n)+sumdiv(n,d,if((d>1)&&(d<n), A191150(d), 0)));
%o A378210 memoA378210 = Map();
%o A378210 A378210(n) = if(1==n,1,my(v); if(mapisdefined(memoA378210,n,&v), v, v = -sumdiv(n,d,if(d<n,A191150(n/d)*A378210(d),0)); mapput(memoA378210,n,v); (v)));
%Y A378210 Cf. A191150.
%Y A378210 Cf. also A378211.
%K A378210 sign
%O A378210 1,2
%A A378210 _Antti Karttunen_, Nov 22 2024