A321771 Numbers whose digit product equals the number of their digits.

1, 12, 21, 113, 131, 311, 1114, 1122, 1141, 1212, 1221, 1411, 2112, 2121, 2211, 4111, 11115, 11151, 11511, 15111, 51111, 111116, 111123, 111132, 111161, 111213, 111231, 111312, 111321, 111611, 112113, 112131, 112311, 113112, 113121, 113211, 116111, 121113

Offset: 1

Author

Ivan Stoykov, Nov 21 2018

Keywords

• nonn
• base

Comments

Idea is similar to A061384, which uses addition instead of multiplication.

Examples

			12 has two digits, and their product is also 2, as 1*2=2.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A061384.

Cf. A007954, A055642. Subsequence of A007602.

Subsequence of A052382 (zeroless numbers).

Programs

Mathematica

Select[Range[1000000], Length[IntegerDigits[#]] == Times @@ IntegerDigits[#] &] (* Amiram Eldar, Nov 21 2018 *)

PARI

isok(n) = my(d=digits(n)); vecprod(d) == #d; \\ Michel Marcus, Nov 22 2018

Extensions

More terms from Amiram Eldar, Nov 21 2018