

A321910


Base7 deletable primes (written in base 10).


2



2, 3, 5, 17, 19, 23, 31, 37, 41, 47, 101, 103, 131, 137, 139, 149, 163, 167, 191, 199, 223, 227, 233, 241, 251, 263, 293, 311, 313, 317, 331, 691, 709, 719, 727, 733, 787, 823, 853, 877, 887, 919, 929, 937, 977, 983, 997, 1013, 1019, 1021, 1031, 1049, 1129, 1171, 1367, 1399, 1409, 1511
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OFFSET

1,1


COMMENTS

A prime p is a baseb 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..808


MATHEMATICA

b = 7; 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, A096235A096246.
Sequence in context: A214697 A035089 A045313 * A045314 A129943 A129673
Adjacent sequences: A321907 A321908 A321909 * A321911 A321912 A321913


KEYWORD

nonn,base,easy


AUTHOR

Robert Price, Nov 29 2018


STATUS

approved



