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A262195 Primes that are the concatenation 1, k! and 1, for some integer k. 0

%I

%S 150401,13628801,136288001,113076743680001

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

%C Inspired by A089764.

%e For n = 1, k = 7, 7! = 5040, and a(1) = 150401 is a prime number.

%t Select[Table[FromDigits[Flatten[{(1), IntegerDigits[n!], {1}}]], {n, 1000}], PrimeQ] (* _Vincenzo Librandi_, Sep 15 2015 *)

%o (PARI) for(n=1, 1e3, if(isprime(k=eval(Str(1,n!,1))), print1(k", ")))

%o (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

%Y Cf. A089764.

%K nonn,hard,base

%O 1,1

%A _Altug Alkan_, Sep 14 2015

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Last modified May 22 06:54 EDT 2022. Contains 353933 sequences. (Running on oeis4.)