A343223 a(n) = gcd(A003415(n), A003415(sigma(n))-n), where A003415 is the arithmetic derivative, and sigma is the sum of divisors of n.

1, 1, 1, 1, 1, 5, 1, 12, 2, 1, 1, 4, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 4, 2, 15, 1, 32, 1, 1, 1, 1, 1, 1, 1, 4, 1, 3, 1, 1, 1, 1, 1, 16, 13, 5, 1, 16, 1, 1, 5, 1, 1, 1, 1, 4, 1, 1, 1, 4, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 16, 3, 1, 1, 1, 1, 1, 1, 4, 1, 3, 1, 4, 1, 3, 1, 48, 1, 1, 1, 8, 1, 1, 1, 2, 1, 1, 1, 1, 1

Offset

1,6

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences related to sigma(n)

Formula

a(n) = gcd(A003415(n), A342926(n)).

Prog

(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A342926(n) = (A003415(sigma(n))-n);
A343223(n) = gcd(A003415(n), A342926(n));

Crossrefs

Cf. A000203, A003415, A342925, A342926.

Sequence in context: A351573 A347135 A146993 * A104572 A125232 A116923

Adjacent sequences: A343220 A343221 A343222 * A343224 A343225 A343226

Keyword

nonn

Author

Antti Karttunen, Apr 15 2021

Status

approved