A067367 Primes p such that the number of digits in p! is also prime.

5, 23, 29, 43, 89, 107, 139, 193, 199, 211, 229, 239, 313, 347, 419, 457, 587, 641, 661, 673, 701, 739, 863, 877, 1091, 1097, 1103, 1217, 1259, 1283, 1361, 1381, 1447, 1493, 1549, 1607, 1609, 1663, 1693, 1741, 1861, 1973, 1987, 2083, 2251, 2351, 2399, 2423

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..450

Example

a(1)=5 because 5!=120 has 3 (prime) digits.

Mathematica

Select[ Select[ Range[2500], PrimeQ[ Floor[ Log[10, #! ] + 1]] & ], PrimeQ[ # ] & ]
Select[Prime[Range[400]], PrimeQ[IntegerLength[#!]]&] (* Harvey P. Dale, Mar 08 2018 *)

Crossrefs

Cf. A035065.

Sequence in context: A084411 A336300 A243458 * A140386 A105880 A163587

Adjacent sequences: A067364 A067365 A067366 * A067368 A067369 A067370

Keyword

nonn,base

Author

Sudipta Das (juitech(AT)vsnl.net), Feb 23 2002

Extensions

Edited and extended by Robert G. Wilson v, Feb 28 2002

Status

approved