A199986 Numbers with digital product = 2.

2, 12, 21, 112, 121, 211, 1112, 1121, 1211, 2111, 11112, 11121, 11211, 12111, 21111, 111112, 111121, 111211, 112111, 121111, 211111, 1111112, 1111121, 1111211, 1112111, 1121111, 1211111, 2111111, 11111112, 11111121, 11111211, 11112111, 11121111, 11211111

Offset

1,1

Comments

Subsequence of A034049.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

S. Giraudo, Combinatorial operads from monoids, arXiv preprint arXiv:1306.6938 [math.CO], 2013-2015. See Sect. 3.2.1.

Maple

f:= proc(d) local b, i;
  b:= (10^d-1)/9;
  seq(b+10^i, i=0..d-1);
end proc:
seq(f(d), d=1..9); # Robert Israel, Jan 13 2021

Prog

(PARI) one(n)=if(n, 10^n\9, "")
for(n=0, 9, for(m=0, n, print1(one(n-m)2one(m)", "))) \\ Charles R Greathouse IV, Nov 13 2011
(Python)
def athrough(k1s):
  return [int("1"*(i-j)+"2"+"1"*j) for i in range(k1s+1) for j in range(i+1)]
print(athrough(8)) # Michael S. Branicky, Feb 12 2021

Crossrefs

Sequence in context: A053896 A155890 A213969 * A336528 A077410 A211029

Adjacent sequences: A199983 A199984 A199985 * A199987 A199988 A199989

Keyword

nonn,easy,base

Author

Jaroslav Krizek, Nov 13 2011

Status

approved