A159251 Composite numbers whose digit sum is a single-digit prime.

12, 14, 16, 20, 21, 25, 30, 32, 34, 50, 52, 70, 102, 104, 106, 110, 111, 115, 120, 122, 124, 133, 140, 142, 160, 200, 201, 203, 205, 210, 212, 214, 221, 230, 232, 250, 300, 302, 304, 320, 322, 340, 403, 410, 412, 430, 500, 502, 511, 520, 610, 700, 1001, 1002

Offset: 1

Author

Parthasarathy Nambi, Apr 06 2009

Keywords

• nonn
• base
• easy
• less

Comments

Numbers of (2..6)-digit terms are 12, 40, 105, 260, 543. - Zak Seidov, Apr 12 2009

Examples

			250 is a composite number whose digit sum of 7 is a single-digit prime.
		

Crossrefs

Cf. A002808 (composite numbers), A157496.

Programs

Mathematica

s={};Do[t=Total[IntegerDigits[n]];If[ !PrimeQ[n]&&(t-2)(t-3)(t-5)(t-7)== 0,AppendTo[s,n]],{n,7*10^3}];s (* Zak Seidov, Apr 12 2009 *)

Extensions

Extended, minor edits and keywords easy, less added by Klaus Brockhaus, Apr 12 2009

More terms from Zak Seidov, Apr 12 2009