A296081 a(n) = gcd(tau(n)-1, sigma(n)-1), where tau = A000005 and sigma = A000203.

0, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 5, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 1, 1, 7, 1, 7, 1, 1, 1, 1, 1, 1, 1, 6, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 5, 5, 8, 1, 1, 1, 1, 1

Offset: 1

Author

Antti Karttunen, Dec 05 2017

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384

Crossrefs

Cf. A032741, A039653, A065608, A284288, A296082, A296083.

Cf. also A009205.

Programs

Mathematica

Array[GCD[DivisorSigma[0,#]-1,DivisorSigma[1,#]-1]&,120] (* Harvey P. Dale, Oct 18 2022 *)

Scheme

(define (A296081 n) (gcd (A039653 n) (A032741 n)))

Formula

a(n) = gcd(A032741(n), A039653(n)).

a(n) = gcd(A039653(n), A065608(n)).