A263131 Ordinal transform of the multiplicative persistence A031346.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 1, 2, 3, 4, 5, 16, 17, 18, 19, 6, 7, 8, 9, 10, 1, 20, 21, 22, 11, 12, 13, 14, 2, 15, 3, 23, 24, 16, 17, 18, 4, 19, 5, 20, 6, 25, 26, 21, 22, 23, 24, 7, 25, 8, 9, 27, 28, 26, 27

Offset

0,2

Comments

n is the a(n)-th nonnegative integer having its multiplicative persistence.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..20000

Eric Weisstein's World of Mathematics, Multiplicative Persistence

Formula

a(n) = |{ j in {0..n} : A031346(j) = A031346(n) }|.

Maple

m:= n-> mul(i, i=convert(n, base, 10)):
p:= n-> `if`(n<10, 0, 1+p(m(n))):
b:= proc() 0 end:
a:= proc(n) option remember; local t;
      t:= p(n); b(t):= b(t)+1
    end:
seq(a(n), n=0..100);

Crossrefs

Cf. A031346.

Sequence in context: A365762 A010889 A053831 * A349315 A274206 A214949

Adjacent sequences: A263128 A263129 A263130 * A263132 A263133 A263134

Keyword

nonn,look,base

Author

Alois P. Heinz, Oct 10 2015

Status

approved