OFFSET
1,2
COMMENTS
The largest prime I have found pertaining to this sequence is A109016(Fibonacci(9837)) with 2064 digits (not proved prime, only Fermat and Lucas PRP).
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..10000
EXAMPLE
193 is in the sequence because 1!+9!+3! = 362887 and 193362887 is prime.
MATHEMATICA
Select[Range[780], PrimeQ[FromDigits[Join[IntegerDigits[#], IntegerDigits[Total[IntegerDigits[#]!]]]]]&] (* James C. McMahon, Feb 22 2024 *)
PROG
(Python)
from math import factorial
from sympy import isprime
def ok(n):
return isprime(int((s:=str(n))+str(sum(factorial(int(d)) for d in s))))
print([k for k in range(999) if ok(k)]) # Michael S. Branicky, Feb 22 2024
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Jason Earls, Jun 18 2005
STATUS
approved