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A096244
Number of n-digit base-11 deletable primes.
0
4, 16, 73, 288, 1117, 4472, 18120, 74643, 315174, 1348936
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. "Digit" means digit in base b.
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.
MATHEMATICA
b = 11; a = {4}; d = {2, 3, 5, 7};
For[n = 2, n <= 5, n++,
p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];
ct = 0;
For[i = 1, i <= Length[p], i++,
c = IntegerDigits[p[[i]], b];
For[j = 1, j <= n, j++,
t = Delete[c, j];
If[t[[1]] == 0, Continue[]];
If[MemberQ[d, FromDigits[t, b]], AppendTo[d, p[[i]]]; ct++;
Break[]]]];
AppendTo[a, ct]];
a (* Robert Price, Nov 13 2018 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Michael Kleber, Feb 28 2003
EXTENSIONS
5 more terms from Ryan Propper, Jul 19 2005
STATUS
approved