A306569 a(n) is the largest value obtained by iterating x -> noz(x * n) starting from 1 (where noz(k) = A004719(k) omits the zeros from k) if any, otherwise a(n) = -1.

1, 765257552, 4858337151, 62987487698944, 14281197489647865625, 16756687971893376, 956884714362661, 292452281337511936, 11897243269649199, 1, 824281567746336491, 13552472793415699584, 841944776182612378933, 9434962871842528764976

Offset

1,2

Comments

Is every term positive?

Links

Rémy Sigrist, Table of n, a(n) for n = 1..250

Rémy Sigrist, PARI program for A306569

Formula

a(10^k) = 1 for any k >= 0.

a(10*n) = a(n) for any n > 0.

Example

a(2) = max(A242350) = 765257552.

Prog

(PARI) See Links section.

Crossrefs

See A306567 for the additive variant.

Cf. A004719, A242350.

Sequence in context: A015370 A068725 A104932 * A118876 A157788 A058420

Adjacent sequences: A306566 A306567 A306568 * A306570 A306571 A306572

Keyword

nonn,base

Author

Rémy Sigrist, Feb 24 2019

Status

approved