A208273 Composite numbers containing a digit 2.

12, 20, 21, 22, 24, 25, 26, 27, 28, 32, 42, 52, 62, 72, 82, 92, 102, 112, 120, 121, 122, 123, 124, 125, 126, 128, 129, 132, 142, 152, 162, 172, 182, 192, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221

Offset: 1

Author

Jaroslav Krizek, Mar 04 2012

Keywords

• nonn
• base

Comments

Subsequence of A011532. Complement of A208272 with respect to A011532.

Links

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

Crossrefs

Cf. A208272 (primes containing a digit 2), A011532 (numbers containing a digit 2).

Programs

Maple

filter:= proc(n) not isprime(n) and member(2,convert(n,base,10)) end proc:
select(filter, [$4..300]); # Robert Israel, Oct 09 2024

Mathematica

Select[Range[300], ! PrimeQ[#] && MemberQ[IntegerDigits[#], 2] &] (* T. D. Noe, Mar 06 2012 *)
Select[Range[300],CompositeQ[#]&&DigitCount[#,10,2]>0&] (* Harvey P. Dale, Sep 08 2024 *)