cp's OEIS Frontend

A346481 a(n) = A346467(n) / A346466(n) = lcm S / lcm {d in S, d+1 | n}, with S = {d | n-1, d+1 is prime}.

%I A346481 #12 Nov 24 2021 09:27:27
%S A346481 1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,10,1,1,1,3,1,1,1,1,1,1,1,8,1,
%T A346481 2,1,1,1,1,1,1,1,1,1,11,1,1,1,8,1,5,1,1,1,18,1,14,1,1,1,1,1,1,1,4,1,1,
%U A346481 1,2,1,1,1,1,1,1,1,4,1,1,1,40,1,1,1,21,1,1,1,1,1,15,1,46,1,2,1,1,1,1,1,1,1,1,1,13
%N A346481 a(n) = A346467(n) / A346466(n) = lcm S / lcm {d in S, d+1 | n}, with S = {d | n-1, d+1 is prime}.
%H A346481 Antti Karttunen, <a href="/A346481/b346481.txt">Table of n, a(n) for n = 1..20000</a>
%F A346481 a(n) = A346467(n) / A346466(n).
%o A346481 (PARI) A346481(n) = if(1==n,n,my(m1=1,m2=1); fordiv(n-1,d,if(isprime(1+d), m1 = lcm(m1,d); if(!(n%(1+d)), m2 = lcm(m2,d)))); (m1/m2));
%Y A346481 Cf. A346466, A346467.
%K A346481 nonn
%O A346481 1,9
%A A346481 _Antti Karttunen_, Jul 31 2021