The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A322443 Base-8 deletable primes (written in base 10). 3
 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 83, 89, 101, 107, 109, 131, 137, 139, 151, 157, 163, 167, 179, 181, 191, 197, 199, 211, 223, 229, 233, 239, 251, 269, 277, 293, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 421, 431, 443, 461, 467, 479, 491 (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. 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 Michael S. Branicky, Table of n, a(n) for n = 1..10000 (terms 1..566 from Robert Price) MATHEMATICA b = 8; 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 08 2018 *) PROG (Python) from sympy import isprime def ok(n):     if not isprime(n): return False     if n < 8: return True     o = oct(n)[2:]     oi = (o[:i]+o[i+1:] for i in range(len(o)))     return any(t[0] != '0' and ok(int(t, 8)) for t in oi) print([k for k in range(492) if ok(k)]) # Michael S. Branicky, Jan 13 2022 CROSSREFS Cf. A080608, A080603, A096235-A096246. Sequence in context: A233360 A234960 A118850 * A219697 A078668 A038614 Adjacent sequences:  A322440 A322441 A322442 * A322444 A322445 A322446 KEYWORD nonn,base,easy AUTHOR Robert Price, Dec 08 2018 STATUS approved

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

Last modified May 22 20:08 EDT 2022. Contains 353957 sequences. (Running on oeis4.)