A046884 Doubly automorphic primes: p is k-th prime, ends in k and k is itself prime.

17, 99551, 14968819, 95517973

Offset

1,1

Links

Table of n, a(n) for n=1..4.

Index entries for sequences related to automorphic numbers

Example

p(7)=17 with 7 and 17 both primes. p(9551)=99551 with both 9551 and 99551 primes.

Mathematica

Select[Prime[Prime[Range[6000000]]], PrimePi[#]==Mod[ #, 10^IntegerLength[ PrimePi[#]]]&] (* The program takes a long time to run *) (* Harvey P. Dale, Jul 05 2012 *)
Prime[Select[Range[5517973], PrimeQ[#]&&StringEndsQ[ToString[Prime[#]], ToString[#]]&]] (* Much faster *) (* Ivan N. Ianakiev, Mar 23 2022 *)

Crossrefs

Cf. A046883.

Sequence in context: A013760 A078351 A046883 * A269442 A203677 A099499

Adjacent sequences: A046881 A046882 A046883 * A046885 A046886 A046887

Keyword

base,hard,nice,nonn

Author

Felice Russo and Carlos Rivera

Status

approved