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 A178327 Numbers n such that n^p+p is prime, where p is product of the digits of n. 1
 1, 21, 6617, 12131, 12441, 114917, 121221, 124281, 125121, 145581, 172631, 182121, 191213, 211551, 221211, 221421, 241213 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS All terms are odd. Large numbers corresponding to some terms are probable prime. There is no further term up to 27500. 254597 < a(18) <= 293143. a(19) <= 421531. a(20) <= 421821. [From Donovan Johnson, Aug 09 2010] LINKS EXAMPLE 21^(2*1)+(2*1) is prime so 21 is in the sequence. MATHEMATICA Do[p=Apply[Times, IntegerDigits[n]]; If[PrimeQ[n^p+p], Print[n]], {n, 1, 27501, 2}] CROSSREFS Cf. A178328. Sequence in context: A220552 A275053 A028451 * A231906 A250063 A307931 Adjacent sequences:  A178324 A178325 A178326 * A178328 A178329 A178330 KEYWORD base,more,nonn AUTHOR Farideh Firoozbakht, May 29 2010 EXTENSIONS No more terms less than 56600. [From Robert G. Wilson v, Jul 27 2010] a(6)-a(17) from Donovan Johnson, Aug 09 2010 STATUS approved

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Last modified December 9 07:21 EST 2021. Contains 349627 sequences. (Running on oeis4.)