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Numbers whose digit product equals the number of their digits.
1

%I #38 Nov 23 2018 03:52:39

%S 1,12,21,113,131,311,1114,1122,1141,1212,1221,1411,2112,2121,2211,

%T 4111,11115,11151,11511,15111,51111,111116,111123,111132,111161,

%U 111213,111231,111312,111321,111611,112113,112131,112311,113112,113121,113211,116111,121113

%N Numbers whose digit product equals the number of their digits.

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

%H Giovanni Resta, <a href="/A321771/b321771.txt">Table of n, a(n) for n = 1..10000</a>

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

%t Select[Range[1000000], Length[IntegerDigits[#]] == Times @@ IntegerDigits[#] &] (* _Amiram Eldar_, Nov 21 2018 *)

%o (PARI) isok(n) = my(d=digits(n)); vecprod(d) == #d; \\ _Michel Marcus_, Nov 22 2018

%Y Cf. A061384.

%Y Cf. A007954, A055642. Subsequence of A007602.

%Y Subsequence of A052382 (zeroless numbers).

%K nonn,base

%O 1,2

%A _Ivan Stoykov_, Nov 21 2018

%E More terms from _Amiram Eldar_, Nov 21 2018