A321657 Base-4 deletable primes (written in base 10).

2, 3, 7, 11, 13, 19, 23, 29, 31, 43, 47, 53, 59, 61, 67, 71, 79, 83, 103, 107, 109, 113, 127, 139, 151, 157, 163, 167, 173, 179, 181, 191, 197, 211, 223, 227, 229, 239, 241, 251, 263, 269, 271, 283, 307, 311, 317, 331, 359, 383, 397, 419, 431, 433, 439, 443

Offset

1,1

Comments

A prime p is a base-b deletable prime if when written in base b it has the property that removing some digit leaves either the empty string or another deletable prime.

Deleting a digit cannot leave any leading zeros in the new string. For example, deleting the 2 in 2003 to obtain 003 is not allowed.

Links

Robert Price, Table of n, a(n) for n = 1..2796

Mathematica

b = 4; d = {};
p = Select[Range[2, 10000], PrimeQ[#] &];
For[i = 1, i <= Length[p], i++,
  c = IntegerDigits[p[[i]], b];
  If[Length[c] == 1, AppendTo[d, p[[i]]]; Continue[]];
  For[j = 1, j <= Length[c], j++,
   t = Delete[c, j];
   If[t[[1]] == 0, Continue[]];
   If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; Break[]]]];
d (* Robert Price, Dec 06 2018 *)

Crossrefs

Cf. A080608, A080603, A096235-A096246.

Sequence in context: A171595 A106483 A145673 * A040116 A155153 A014580

Adjacent sequences: A321654 A321655 A321656 * A321658 A321659 A321660

Keyword

nonn,base,easy

Author

Robert Price, Nov 15 2018

Status

approved