A157676 Numbers n such that n + (product of digits of n) is prime.

1, 21, 23, 27, 29, 61, 67, 81, 83, 101, 103, 107, 109, 161, 163, 169, 233, 239, 253, 259, 283, 289, 293, 299, 307, 329, 341, 343, 347, 349, 361, 401, 409, 431, 437, 439, 441, 443, 449, 471, 473, 477, 493, 499, 503, 509, 529, 563, 569, 601, 607, 611, 613, 617

Offset

1,2

Links

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

Formula

a(n) ~ n log n. - Charles R Greathouse IV, Dec 27 2013

Example

a(21) = 21 + (2)(1) = 23 (prime). a(67) = 67 + (6)(7) = 109 (prime). a(169) = 169 + (1)(6)(9) = 223 (prime).

Mathematica

fQ[n_] := PrimeQ[n + Times @@ IntegerDigits@n]; Select[ Range@1000, fQ@# &] (* Robert G. Wilson v, May 04 2009 *)

Prog

(PARI) dprod(n)=n=digits(n); prod(i=1, #n, n[i])
is(n)=isprime(dprod(n)+n) \\ Charles R Greathouse IV, Dec 27 2013

Crossrefs

Cf. A157677, A092518.

Sequence in context: A089787 A329914 A229221 * A227948 A303718 A270108

Adjacent sequences: A157673 A157674 A157675 * A157677 A157678 A157679

Keyword

nonn,base

Author

Kyle D. Balliet, Mar 04 2009

Extensions

More terms from Robert G. Wilson v, May 04 2009

Status

approved