A096244 Number of n-digit base-11 deletable primes.

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.

Links

Table of n, a(n) for n=1..10.

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

Cf. A080608, A080603, A096235-A096246.

Sequence in context: A059371 A208528 A007234 * A030131 A091530 A344248

Adjacent sequences: A096241 A096242 A096243 * A096245 A096246 A096247

Keyword

nonn,base,more

Author

Michael Kleber, Feb 28 2003

Extensions

5 more terms from Ryan Propper, Jul 19 2005

Status

approved