A373249 a(n) = A181819(n) / gcd(n, A181819(n)), where A181819(n) is the prime shadow of n.

1, 1, 2, 3, 2, 2, 2, 5, 1, 2, 2, 1, 2, 2, 4, 7, 2, 1, 2, 3, 4, 2, 2, 5, 3, 2, 5, 3, 2, 4, 2, 11, 4, 2, 4, 1, 2, 2, 4, 1, 2, 4, 2, 3, 2, 2, 2, 7, 3, 3, 4, 3, 2, 5, 4, 5, 4, 2, 2, 1, 2, 2, 2, 13, 4, 4, 2, 3, 4, 4, 2, 5, 2, 2, 2, 3, 4, 4, 2, 7, 7, 2, 2, 1, 4, 2, 4, 5, 2, 2, 4, 3, 4, 2, 4, 11, 2, 3, 2, 9, 2, 4, 2, 5, 8

Offset

1,3

Links

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

Formula

a(n) = A181819(n) / A373246(n) = A181819(n) / gcd(n, A181819(n)).

Prog

(PARI)
A181819(n) = factorback(apply(e->prime(e), (factor(n)[, 2])));
A373249(n) = { my(s=A181819(n)); s/gcd(n, s); };

Crossrefs

Cf. A181819, A373246.

Cf. A325755 (positions of 1's), A353566 (their characteristic function).

Sequence in context: A187757 A286529 A306225 * A077199 A145390 A270026

Adjacent sequences: A373246 A373247 A373248 * A373250 A373251 A373252

Keyword

nonn

Author

Antti Karttunen, May 30 2024

Status

approved