A069867 Primes in which repeatedly deleting the least significant digit then the most significant digit gives a prime at every step until a single-digit prime remains.

2, 3, 5, 7, 23, 29, 31, 37, 53, 59, 71, 73, 79, 131, 137, 139, 173, 179, 233, 239, 373, 379, 431, 433, 439, 479, 673, 677, 733, 739, 839, 971, 977, 1319, 1373, 1733, 2237, 2239, 2293, 2297, 2711, 2713, 2719, 3313, 3319, 3371, 3373, 3533, 3539, 3593, 3733

Offset

1,1

Links

Michael De Vlieger, Table of n, a(n) for n = 1..440 (Primes p <= 5 * 10^7).

Mathematica

Select[Prime@ Range@ 512, AllTrue[FromDigits /@ Rest@ Fold[Append[#1, Delete[Last[#1], 1 - 2 Boole[OddQ@ #2]]] &, {#}, Range[Length@ # - 1]] &@ IntegerDigits[#], PrimeQ] &] (* Michael De Vlieger, Jan 20 2018 *)

Crossrefs

Cf. A033664, A024770, A069866.

Sequence in context: A113590 A124673 A024776 * A320585 A024770 A038603

Adjacent sequences: A069864 A069865 A069866 * A069868 A069869 A069870

Keyword

base,nonn

Author

Amarnath Murthy, Apr 21 2002

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Sep 24 2002

Status

approved