A360942 a(n) is the least k such that k*n is a happy number (A007770).

1, 5, 43, 7, 2, 32, 1, 4, 125, 1, 4, 16, 1, 2, 75, 2, 4, 64, 1, 5, 49, 2, 1, 8, 4, 5, 44, 1, 7, 43, 1, 1, 34, 2, 2, 32, 24, 5, 28, 7, 2, 26, 2, 1, 25, 5, 2, 4, 1, 2, 22, 4, 17, 22, 8, 5, 16, 8, 4, 32, 11, 5, 21, 3, 2, 17, 7, 1, 22, 1, 13, 16, 3, 12, 15, 8, 11

Offset

1,2

Comments

This sequence is well defined (see A360941).

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Formula

a(n) = A360941(n) / n.

a(n) = 1 iff n belongs to A007770.

Prog

(PARI) a(n) = { forstep (m = n, oo, n, my (h = m, d); while (h > 6, d = digits(h); h = sum(k = 1, #d, d[k]^2)); if (h == 1, return (m / n))) }

Crossrefs

Cf. A007770, A360941.

Sequence in context: A368352 A132487 A178614 * A284170 A067927 A038546

Adjacent sequences: A360939 A360940 A360941 * A360943 A360944 A360945

Keyword

nonn,base

Author

Rémy Sigrist, Feb 26 2023

Status

approved