cp's OEIS Frontend

A326047 a(n) = gcd(n-A050449(n), n-A050452(n)), where A050449 and A050452 give the sum of divisors of the form 4k+1 and of the form 4k+3, respectively.

%I A326047 #8 Jun 04 2019 16:33:06
%S A326047 1,1,2,1,1,1,6,1,1,2,10,1,1,1,3,1,1,1,18,2,1,1,22,1,1,2,1,3,1,12,30,1,
%T A326047 1,2,1,1,1,1,1,2,1,4,42,1,3,1,46,1,1,1,3,2,1,4,1,1,1,2,58,6,1,1,2,1,1,
%U A326047 4,66,2,1,4,70,1,1,2,2,3,1,4,78,2,1,2,82,2,1,1,3,1,1,6,7,1,1,1,1,1,1,1,14,1,1,12,102,2,9
%N A326047 a(n) = gcd(n-A050449(n), n-A050452(n)), where A050449 and A050452 give the sum of divisors of the form 4k+1 and of the form 4k+3, respectively.
%H A326047 Antti Karttunen, <a href="/A326047/b326047.txt">Table of n, a(n) for n = 1..65537</a>
%F A326047 a(n) = gcd(A326049(n), A326052(n)) = gcd(n-A050449(n), n-A050452(n)).
%F A326047 a(2n-1) = A326048(2n-1) for all n.
%o A326047 (PARI)
%o A326047 A050449(n) = sumdiv(n, d, d*((d % 4) == 1)); \\ From A050449
%o A326047 A326049(n) = (n-A050449(n));
%o A326047 A050452(n) = sumdiv(n, d, d*(3==(d % 4)));
%o A326047 A326052(n) = (n-A050452(n));
%o A326047 A326047(n) = gcd(A326049(n), A326052(n));
%Y A326047 Cf. A050449, A050452, A326048, A326049, A326052
%K A326047 nonn
%O A326047 1,3
%A A326047 _Antti Karttunen_, Jun 04 2019