A320752 Primes of the form 5*n^2 - 5*n + 13.

13, 23, 43, 73, 113, 163, 223, 293, 373, 463, 563, 673, 1063, 1213, 1373, 1543, 1723, 1913, 2113, 2543, 3793, 4073, 4363, 4663, 4973, 5623, 6673, 7043, 8623, 9043, 9473, 12263, 12763, 14323, 15413, 15973, 17123, 17713, 18313, 19543, 20173, 22123, 23473, 26293

Offset: 1

Author

Arashdeep Singh, Oct 20 2018

Keywords

• nonn

Comments

The first 12 numbers of the form 5*n^2 - 5*n + 13 (n=1 to 12) are primes.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A090562.

Programs

GAP

Filtered(List([1..75],n->5*n^2-5*n+13),IsPrime); # Muniru A Asiru, Oct 21 2018

Maple

select(isprime,[seq(5*n^2-5*n+13,n=1..75)]); # Muniru A Asiru, Oct 21 2018

Mathematica

Select[Table[5n^2-5n+13,{n,80}],PrimeQ] (* Harvey P. Dale, Aug 22 2021 *)

PARI

terms(n) = my(i=0); for(k=1, oo, my(x=5*k^2-5*k+13); if(ispseudoprime(x), print1(x, ", "); i++); if(i==n, break))
/* Print initial 50 terms as follows */
terms(50) \\ Felix Fröhlich, Oct 20 2018

Extensions

More terms from Felix Fröhlich, Oct 20 2018