A069866 Primes in which repeatedly deleting the most significant digit then the least significant digit gives a prime at every step until a single-digit prime remains.

2, 3, 5, 7, 13, 17, 23, 37, 43, 47, 53, 67, 73, 83, 97, 131, 137, 173, 179, 223, 229, 271, 331, 337, 353, 359, 373, 379, 431, 479, 523, 571, 631, 653, 659, 673, 773, 823, 829, 853, 859, 929, 937, 953, 971, 1031, 1373, 1433, 1439, 1733, 2029, 2053, 2131, 2137

Offset

1,1

Links

Michael De Vlieger, Table of n, a(n) for n = 1..645 (Primes p <= 10^7).

Mathematica

Select[Prime@ Range@ 400, AllTrue[FromDigits /@ Rest@ Fold[Append[#1, Delete[Last[#1], 1 - 2 Boole[EvenQ@ #2]]] &, {#}, Range[Length@ # - 1]] &@ IntegerDigits[#], PrimeQ] &] (* Michael De Vlieger, Jan 20 2018 *)

Crossrefs

Cf. A024770, A033664, A069867.

Sequence in context: A308711 A033664 A024785 * A125772 A233282 A001000

Adjacent sequences: A069863 A069864 A069865 * A069867 A069868 A069869

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