A143932 a(n) = smallest positive prime number of the form x^2 - n! (where x is a positive integer).

3, 2, 3, 97, 241, 241, 1201, 3361, 5569, 61441, 240769, 915049, 240769, 17302321, 7076521, 49186201, 2100735289, 1074527281, 23971813321, 32354445841, 68820869329, 2992426816129, 26238323995129, 104071698229321

Offset: 1

Author

Artur Jasinski, Sep 05 2008

Keywords

• nonn

Comments

For smallest positive integers x see A143931. Prime x see A143933.

Examples

			a(1)=3 because 2^2 - 1! = 3;
a(2)=2 because 2^2 - 2! = 2;
a(3)=3 because 3^2 - 3! = 3;
a(4)=97 because 11^2 - 4! = 97.
		

Crossrefs

Cf. A121926, A143931, A143933.

Programs

Mathematica

b = {}; Do[k = Round[Sqrt[n! ]] + 1; While[ ! PrimeQ[k^2 - n! ], k++ ]; AppendTo[b, k^2-n! ], {n, 1, 50}]; b