A256621 Primes p such that the decimal expansion of p remains prime under three iterations of base-10 to base-2 conversion.

3893257, 9023533, 11005327, 11659009, 18747809, 21855233, 25183007, 34074379, 54298687, 58562951, 60496981, 89891273, 94277683, 96602887, 102276859, 115555927, 117578429, 122191543, 125115709, 132837283, 138169991, 139442753, 168852077, 183879649, 184904831

Offset: 1

Author

Sebastian Petzelberger, Apr 06 2015

Keywords

• nonn
• base

Examples

			The 3 iterations: 3893257 --> 1110110110100000001001 --> ... --> ... are prime.
		

Links

• Sebastian Petzelberger, Table of n, a(n) for n = 1..10000
• Carlos Rivera, Puzzle 280. 3893257, The Prime Puzzles and Problems Connection.

Crossrefs

Cf. A065720, A123266, A256622.

Programs

PARI

isok(n, nb=3) = {for (k=1, nb, b = binary(n); d = eval(subst(Pol(b), x, 10)); if (! isprime(d), return (0)); n = d;); return (1);} \\ Michel Marcus, Apr 08 2015