This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A125589 Smallest n-digit base-10 deletable prime. 1
 2, 13, 103, 1013, 10039, 100103, 1000193, 10000931, 100001903, 1000003957, 10000003957, 100000013957, 1000000030957, 10000000301957, 100000000730957, 1000000000730957, 10000000003632979, 100000000007309357 (list; graph; refs; listen; history; text; internal format)
 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 MATHEMATICA b = 10; a = {2}; d = {2, 3, 5, 7}; For[n = 2, n <= 6, n++,   found = False;   p = Select[Range[b^(n - 1), b^n - 1], PrimeQ[#] &];   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]]];      If[! found , AppendTo[a, p[[i]]]]; found = True; Break[]]]; ]]; a (* Robert Price, Nov 13 2018 *) CROSSREFS Cf. A080608, A096243, A096246, A125590. Sequence in context: A046893 A126036 A113598 * A007809 A259146 A103513 Adjacent sequences:  A125586 A125587 A125588 * A125590 A125591 A125592 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Jan 07 2007 EXTENSIONS a(6) - a(8) from Michael Kleber, Jan 08 2007 a(9) - a(14) from Phil Carmody, Jan 09 2007 a(15) - a(18) from Joshua Zucker, Jan 09 2007 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 December 15 22:02 EST 2019. Contains 330012 sequences. (Running on oeis4.)