A159251 - OEIS

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

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OFFSET

1,1

COMMENTS

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

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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 (* Zak Seidov, Apr 12 2009 *)

Select[Range[1100], CompositeQ[#]&&MemberQ[{2, 3, 5, 7}, Total[IntegerDigits[#]]]&] (* Harvey P. Dale, Nov 26 2025 *)

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