The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A178327 Numbers k such that k^p+p is prime, where p is product of the digits of k. 1
 1, 21, 6617, 12131, 12441, 114917, 121221, 124281, 125121, 145581, 172631, 182121, 191213, 211551, 221211, 221421, 241213, 293143, 421531, 421821 (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. - Donovan Johnson, Aug 09 2010 LINKS Table of n, a(n) for n=1..20. EXAMPLE 21^(2*1)+(2*1) is prime so 21 is a term. MATHEMATICA Do[p=Apply[Times, IntegerDigits[n]]; If[PrimeQ[n^p+p], Print[n]], {n, 1, 27501, 2}] CROSSREFS Cf. A178328, A099227. 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. - Robert G. Wilson v, Jul 27 2010 a(6)-a(17) from Donovan Johnson, Aug 09 2010 a(18)-a(20) from Michael S. Branicky, Jun 23 2023 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 23 16:36 EDT 2024. Contains 372765 sequences. (Running on oeis4.)