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

1,1

Comments

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

Links

Table of n, a(n) for n=1..54.

Example

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

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 [From Zak Seidov, Apr 12 2009]

Crossrefs

Cf. A002808 (composite numbers), A157496.

Sequence in context: A096923 A141642 A163622 * A208156 A135770 A091989

Adjacent sequences: A159248 A159249 A159250 * A159252 A159253 A159254

Keyword

nonn,base,easy,less

Author

Parthasarathy Nambi, Apr 06 2009

Extensions

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

More terms from Zak Seidov, Apr 12 2009

Status

approved