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A157676 Numbers n such that n + (product of digits of n) is prime. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 20 17:47 EDT 2022. Contains 353876 sequences. (Running on oeis4.)