A262195 Primes that are the concatenation 1, k! and 1, for some integer k.

150401, 13628801, 136288001, 113076743680001

Offset

1,1

Comments

Inspired by A089764.

Links

Table of n, a(n) for n=1..4.

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

Cf. A089764.

Sequence in context: A254239 A051651 A065324 * A138264 A343679 A246285

Adjacent sequences: A262192 A262193 A262194 * A262196 A262197 A262198

Keyword

nonn,hard,base

Author

Altug Alkan, Sep 14 2015

Status

approved