A228019 Composite numbers whose sum of digits is a composite number.

4, 6, 8, 9, 15, 18, 22, 24, 26, 27, 28, 33, 35, 36, 39, 40, 42, 44, 45, 46, 48, 51, 54, 55, 57, 60, 62, 63, 64, 66, 68, 69, 72, 75, 77, 78, 80, 81, 82, 84, 86, 87, 88, 90, 91, 93, 95, 96, 99, 105, 108, 112, 114, 116, 117, 118, 121, 123, 125, 126, 129, 130, 132

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

87 is a term: 87 and 8+7=15 are composite.

Prog

(PARI) lista(N) = my(s); for(n=2, N, s=sumdigits(n); if(!isprime(n)&&!isprime(s)&&s>1, print1(n, ", ") ) ) \\ Joerg Arndt, Aug 04 2013
(PARI) list(N)=my(v=List(), s); forcomposite(n=4, N, s=sumdigits(n); if(s>1 && !isprime(s), listput(v, n))); Vec(v)  \\ Charles R Greathouse IV, Aug 13 2013
(Magma) [n: n in [4..200] | not IsPrime(n) and not IsPrime(&+Intseq(n))]; // Bruno Berselli, Aug 13 2013

Crossrefs

Subsequence of A104211.

Sequence in context: A262389 A254755 A275624 * A228020 A163282 A095404

Adjacent sequences: A228016 A228017 A228018 * A228020 A228021 A228022

Keyword

nonn,base,easy

Author

Derek Orr, Aug 02 2013

Status

approved