The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A097223 Prime numbers p such that p = prime(n) and n = product of the digits of p. 10
 17, 73, 2475989 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This sequence is a subsequence of A097220, so the sequence is also a subsequence of A097221. Next term if it exists is greater than 4333000000. There is no further term. [Farideh Firoozbakht, Jul 15 2009] LINKS Chris K. Caldwell and G. L. Honaker, Jr., 2475989 Carl Pomerance, What we still don't know about addition and multiplication, Trjitzinsky Lecture 1, U. Illinois Urbana-Champaign, November 27, 2018. See slides 22 & 24. EXAMPLE 2475989 is in the sequence because 2475989 is (2*4*7*5*9*8*9)-th prime. MATHEMATICA v={}; Do[If[h=IntegerDigits[Prime[n]]; l=Length[h]; p=Product[h[[k]], {k, l}]; p==n, v=Append[v, Prime[n]]; Print[v]], {n, 205000000}] PROG (PARI) isok(p) = isprime(p) && (primepi(p) == vecprod(digits(p))); \\ Michel Marcus, Jan 27 2019 CROSSREFS Cf. A097220, A097221. Sequence in context: A165691 A154419 A208399 * A296113 A231779 A063494 Adjacent sequences:  A097220 A097221 A097222 * A097224 A097225 A097226 KEYWORD base,fini,full,nonn,bref AUTHOR Farideh Firoozbakht, Aug 06 2004 STATUS approved

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

Last modified December 6 04:20 EST 2021. Contains 349562 sequences. (Running on oeis4.)