cp's OEIS Frontend

A331283 a(n) = gcd(n, A329605(n)), where A329605(n) gives the number of divisors of primorial inflation of n, A108951(n).

%I A331283 #12 Jan 14 2020 22:18:56
%S A331283 1,2,1,1,1,6,1,4,9,2,1,4,1,2,3,1,1,6,1,4,3,2,1,2,1,2,1,4,1,6,1,2,3,2,
%T A331283 1,3,1,2,3,20,1,6,1,4,1,2,1,12,1,2,3,4,1,2,1,8,3,2,1,30,1,2,1,1,1,6,1,
%U A331283 4,3,2,1,18,1,2,3,4,1,6,1,8,1,2,1,12,1,2,3,8,1,10,1,4,3,2,1,2,1,2,1,5,1,6,1,8,3
%N A331283 a(n) = gcd(n, A329605(n)), where A329605(n) gives the number of divisors of primorial inflation of n, A108951(n).
%H A331283 Antti Karttunen, <a href="/A331283/b331283.txt">Table of n, a(n) for n = 1..11025</a>
%H A331283 Antti Karttunen, <a href="/A331283/a331283.txt">Data supplement: n, a(n) computed for n = 1..65537</a>
%H A331283 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A331283 <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>
%F A331283 a(n) = gcd(n, A329605(n)).
%F A331283 a(A002110(n)) = gcd(A002110(n), A000142(1+n)) = A034386(1+n), for n >= 0.
%o A331283 (PARI) A331283(n) = if(1==n,1,my(f=factor(n),e=1,m=1); forstep(i=#f~,1,-1, e += f[i,2]; m *= e^(primepi(f[i,1])-if(1==i,0,primepi(f[i-1,1])))); gcd(n,m));
%Y A331283 Cf. A000142, A002110, A034386, A108951, A329605.
%Y A331283 Cf. also A009191, A329612.
%K A331283 nonn
%O A331283 1,2
%A A331283 _Antti Karttunen_, Jan 14 2020