A181576 Primes whose factorials end with a prime number of trailing 0's.

11, 13, 17, 19, 31, 59, 83, 127, 151, 173, 179, 197, 199, 223, 293, 367, 397, 421, 439, 449, 461, 463, 557, 569, 607, 617, 619, 631, 659, 733, 773, 797, 853, 919, 941, 967, 1013, 1039, 1061, 1063, 1087, 1097, 1123, 1181, 1259, 1399, 1423, 1447, 1543, 1567

Offset: 1

Author

Lekraj Beedassy, Nov 02 2010

Keywords

• nonn
• base

Comments

For the corresponding prime number of trailing end 0's, see A181577.

Examples

			The factorial 2! = 2 ends with 0 zeros, so the prime 2 is not in the sequence because 0 is not a prime.
The factorial 5! = 120 ends with 1 zero, so the prime 5 is not in the sequence because 1 is not a prime.
The factorial 11! = 39916800 ends with 2 zeros, so the prime 11 is in the sequence because 2 is a prime.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A027868, A039716, A181577.

Programs

Mathematica

Select[ Prime@ Range@ 250, PrimeQ@ IntegerExponent[ #! ] &] (* Robert G. Wilson v, Nov 06 2010 *)

PARI

is(p) = isprime(p) && isprime((p - sumdigits(p, 5))/4); \\ Amiram Eldar, May 03 2024

Formula

A027868(a(n)) = A181577(n). - Amiram Eldar, May 03 2024

Extensions

More terms from Robert G. Wilson v, Nov 06 2010