OFFSET
1,1
COMMENTS
Inspired by A089764.
EXAMPLE
For n = 1, k = 7, 7! = 5040, and a(1) = 150401 is a prime number.
MATHEMATICA
Select[Table[FromDigits[Flatten[{(1), IntegerDigits[n!], {1}}]], {n, 1000}], PrimeQ] (* Vincenzo Librandi, Sep 15 2015 *)
PROG
(PARI) for(n=1, 1e3, if(isprime(k=eval(Str(1, n!, 1))), print1(k", ")))
(Magma) [m: n in [1..1000] | IsPrime(m) where m is Seqint(Intseq(1) cat Intseq(Factorial(n)) cat Intseq(1))]; // Vincenzo Librandi, Sep 15 2015
CROSSREFS
KEYWORD
nonn,hard,base
AUTHOR
Altug Alkan, Sep 14 2015
STATUS
approved