A230104 Numbers k such that m + (product of digits of m) is never equal to k.

1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 25, 27, 31, 33, 36, 37, 39, 43, 48, 49, 51, 52, 53, 57, 59, 61, 63, 64, 69, 71, 72, 73, 76, 77, 79, 82, 83, 84, 87, 91, 93, 96, 97, 99, 111, 113, 115, 117, 119, 121, 127, 131, 133, 136, 137, 139, 148, 149, 151, 153, 157, 159, 163, 164, 169, 171, 172, 173, 176, 177, 179, 182, 183

Offset: 1

Author

N. J. A. Sloane, Oct 13 2013

Keywords

• nonn
• base

Comments

Numbers missing from A230099.

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000
• Index entries for Colombian or self numbers and related sequences

Crossrefs

Cf. A230099, A230103, A230105.

Programs

PARI

f(n) = if (n, n + vecprod(digits(n)), 0); \\ A230104
isok(m) = for(i=1, m, if (f(i) == m, return(0))); return(1); \\ Michel Marcus, Jan 09 2023

Python

from math import prod
def b(n): return n + prod(map(int, str(n)))
def aupto(n): return sorted(set(range(n+1)) - set(b(m) for m in range(n+1)))
print(aupto(183)) # Michael S. Branicky, Jan 09 2023