A326047 - OEIS

%I #8 Jun 04 2019 16:33:06

%S 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 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 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 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 Antti Karttunen, <a href="/A326047/b326047.txt">Table of n, a(n) for n = 1..65537</a>

%F a(n) = gcd(A326049(n), A326052(n)) = gcd(n-A050449(n), n-A050452(n)).

%F a(2n-1) = A326048(2n-1) for all n.

%o (PARI)

%o A050449(n) = sumdiv(n, d, d*((d % 4) == 1)); \\ From A050449

%o A326049(n) = (n-A050449(n));

%o A050452(n) = sumdiv(n, d, d*(3==(d % 4)));

%o A326052(n) = (n-A050452(n));

%o A326047(n) = gcd(A326049(n), A326052(n));

%Y Cf. A050449, A050452, A326048, A326049, A326052

%K nonn

%O 1,3

%A _Antti Karttunen_, Jun 04 2019