This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A096236 Number of n-digit base-3 deletable primes. 2
 1, 2, 4, 7, 13, 24, 38, 72, 122, 226, 400, 684, 1246, 2381, 4384, 8330, 15839, 30617, 58764, 113987, 221994, 434498, 852036, 1673320, 3296641, 6509179 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 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 MATHEMATICA b = 3; a = {1}; d = {2}; For[n = 2, n <= 10, 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 12 2018 *) CROSSREFS Cf. A080608, A080603, A096235-A096246. Sequence in context: A018182 A005595 A296689 * A002574 A069765 A090427 Adjacent sequences:  A096233 A096234 A096235 * A096237 A096238 A096239 KEYWORD nonn,more,base AUTHOR Michael Kleber, Feb 28 2003 EXTENSIONS More terms from John W. Layman, Dec 14 2004 11 more terms from Ryan Propper, Jul 19 2005 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)