A221698 - OEIS

A221698

Composite numbers n such that largest digit of all divisors of n is 2.

22, 121, 202, 1111, 2222, 10201, 12221, 20222, 22121, 111221, 112211, 202222, 220121, 221111, 222211, 1021211, 1112221, 1122011, 1222201, 2021111, 2022002, 2022121, 2121101, 2122111, 2200202, 2202211, 2211121, 2212111, 2222011, 10212211, 11112211, 11121011

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OFFSET

1,1

COMMENTS

Also composite numbers n such that largest digit of concatenation of all divisors (A037278) of n is 2.

Composite numbers n such that A209928(n) = 2.

Complement of A106100 with respect to A221697.

LINKS

Table of n, a(n) for n=1..32.

EXAMPLE

Number 10201 is in the sequence because the largest digit of all divisors of 10201 (1, 101, 10201) is 2.

MATHEMATICA

t = {}; n = 1; While[Length[t] < 40, n++; m = FromDigits[IntegerDigits[n, 3]]; If[! PrimeQ[m] && Max[Union[Flatten[IntegerDigits[Divisors[m]]]]] <= 2, AppendTo[t, m]]]; t (* T. D. Noe, Jan 30 2013 *)

CROSSREFS

Cf. A209928 (largest digit of all divisors of n), A221697.

Sequence in context: A251930 A039612 A085828 * A081931 A156293 A225308

Adjacent sequences: A221695 A221696 A221697 * A221699 A221700 A221701

KEYWORD

nonn,base

AUTHOR

Jaroslav Krizek, Jan 22 2013

STATUS

approved