A118693 Semiprimes which are divisible by the sum of their digits.

4, 6, 9, 10, 21, 111, 133, 201, 209, 247, 407, 481, 511, 629, 803, 1011, 1101, 1141, 1387, 1417, 1651, 1679, 1853, 2119, 2159, 2353, 2771, 3031, 3077, 3097, 3383, 3439, 3523, 3749, 3781, 4577, 4607, 5149, 5161, 5219, 5833, 6331, 6443, 7033, 7361, 7501

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

133 is in the sequence because it is a semiprime and it is divisible by the sum of its digits, 1+3+3 = 7.

Mathematica

spQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; Select[Range@7542, spQ@# && IntegerQ[ #/Plus @@ IntegerDigits@# ] &] (* Robert G. Wilson v, Jun 10 2006 *)

Crossrefs

Intersection of A001358 and A005349.

Cf. A118694.

Sequence in context: A118695 A235108 A215478 * A084668 A085842 A356135

Adjacent sequences: A118690 A118691 A118692 * A118694 A118695 A118696

Keyword

base,nonn

Author

Luc Stevens (lms022(AT)yahoo.com), May 20 2006

Extensions

More terms from Robert G. Wilson v, Jun 10 2006

Status

approved