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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. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 24 18:12 EDT 2019. Contains 326295 sequences. (Running on oeis4.)