OFFSET
1,1
COMMENTS
Primes of the form (15*k^2 - 15*k + 2)/2.
All the terms in this sequence are congruent to 1 (mod 10). - K. D. Bajpai, Nov 29 2015
The associated k-values are 5, 8, 9, 12, 13, 16, 20, 29, 40, 41, 45, 48, 52, 64, 68, 76, 77, 84, 85, 89, ... - Danny Rorabaugh, Jan 18 2016
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..10000
OEIS Wiki, Figurate numbers
Eric Weisstein's World of Mathematics, Centered Polygonal Number and Prime Number
MAPLE
select(isprime, [seq((15*k^2 - 15*k + 2) / 2, k=0..1000)]); # K. D. Bajpai, Nov 29 2015
MATHEMATICA
Select[Table[(15n^2 - 15n + 2) / 2, {n, 500}], PrimeQ] (* K. D. Bajpai, Nov 29 2015 *)
PROG
(PARI) for(n=1, 1e3, if(isprime(k=(15*n^2-15*n+2)/2), print1(k, ", "))) \\ Altug Alkan, Nov 26 2015
(Magma) [k: n in [1..10000] | IsPrime(k) where k is (15*n^2-15*n+2) div 2]; // K. D. Bajpai, Nov 29 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 26 2015
STATUS
approved