A062231 Numbers k such that the smoothly undulating palindromic number (97*10^k - 79)/99 is a prime.

9, 27, 45, 237

Offset

1,1

Comments

Prime versus probable prime status and proofs are given in the author's table.

No further terms < 100000. - Ray Chandler, Aug 17 2011

Links

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

Patrick De Geest, SUPP Reference Table - 979

Index entries for sequences related to smoothly undulating palindromic primes

Example

k=27 -> (97*10^27 - 79)/99 = 979797979797979797979797979.

Mathematica

Select[Range[1, 239, 2], PrimeQ[FromDigits[PadRight[{}, #, {9, 7}]]]&] (* Harvey P. Dale, Mar 24 2021 *)

Crossrefs

Cf. A062209-A062232, A059758, A032758.

Sequence in context: A020156 A342869 A287661 * A133636 A369564 A020208

Adjacent sequences: A062228 A062229 A062230 * A062232 A062233 A062234

Keyword

nonn,base,more

Author

Patrick De Geest and Hans Rosenthal (Hans.Rosenthal(AT)t-online.de), Jun 15 2001

Extensions

Edited by Ray Chandler, Aug 17 2011

Status

approved