|
%I #4 Dec 27 2013 09:51:17
%S 1,21,23,27,29,61,67,81,83,101,103,107,109,161,163,169,233,239,253,
%T 259,283,289,293,299,307,329,341,343,347,349,361,401,409,431,437,439,
%U 441,443,449,471,473,477,493,499,503,509,529,563,569,601,607,611,613,617
%N Numbers n such that n + (product of digits of n) is prime.
%H Charles R Greathouse IV, <a href="/A157676/b157676.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) ~ n log n. - _Charles R Greathouse IV_, Dec 27 2013
%e a(21) = 21 + (2)(1) = 23 (prime). a(67) = 67 + (6)(7) = 109 (prime). a(169) = 169 + (1)(6)(9) = 223 (prime).
%t fQ[n_] := PrimeQ[n + Times @@ IntegerDigits@n]; Select[ Range@1000, fQ@# &] (* _Robert G. Wilson v_, May 04 2009 *)
%o (PARI) dprod(n)=n=digits(n);prod(i=1,#n,n[i])
%o is(n)=isprime(dprod(n)+n) \\ _Charles R Greathouse IV_, Dec 27 2013
%Y Cf. A157677, A092518.
%K nonn,base
%O 1,2
%A _Kyle D. Balliet_, Mar 04 2009
%E More terms from _Robert G. Wilson v_, May 04 2009
|
