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A322471
Base-9 deletable primes (written in base 10).
2
2, 3, 5, 7, 11, 19, 23, 29, 31, 41, 43, 47, 53, 59, 61, 67, 71, 79, 83, 101, 103, 107, 137, 163, 167, 173, 179, 181, 191, 193, 199, 211, 223, 229, 233, 239, 241, 263, 269, 281, 283, 317, 331, 347, 349, 353, 367, 373, 383, 389, 401, 431, 443, 449, 461, 467, 479, 491, 509, 547, 557, 563
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
MATHEMATICA
b = 9; 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 09 2018 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Robert Price, Dec 09 2018
STATUS
approved