A031355 - OEIS

A031355

9-multiplicative persistence: number of iterations of "multiply 9th powers of digits" needed to reach 0 or 1.

0, 3, 3, 3, 3, 2, 2, 3, 2, 1, 1, 3, 3, 3, 3, 2, 2, 3, 2, 1, 3, 3, 2, 3, 2, 2, 2, 3, 2, 1, 3, 2, 2, 2, 3, 2, 2, 2, 3, 1, 3, 3, 2, 3, 2, 2, 2, 2, 2, 1, 3, 2, 3, 2, 3, 2, 3, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 3, 2, 2, 3, 3, 1, 3, 3, 2, 2, 2, 2, 3, 2, 3, 1, 2, 2, 3, 2, 2, 2, 3, 3, 2

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Multiplicative Persistence

PROG

(Magma) pers:=func<n, e|&*[c^e:c in Intseq(n)]>; a:=[0]; for n in [2..100] do m:=1; k:=n; while not pers(k, 9) in {0, 1} do k:=pers(k, 9); m:=m+1; end while; Append(~a, m); end for; a; // Marius A. Burtea, Jan 13 2020

CROSSREFS

Sequence in context: A081334 A106694 A183051 * A337265 A177228 A247655

Adjacent sequences: A031352 A031353 A031354 * A031356 A031357 A031358

KEYWORD

nonn,base

AUTHOR

Eric W. Weisstein

EXTENSIONS

Offset 1 from Seiichi Manyama, Jan 13 2020

STATUS

approved