OFFSET
1,1
COMMENTS
Primes of the form 11*k^2 + 11*k + 1.
Numbers k such that 11*k^2 + 11*k + 1 is prime: 1, 2, 5, 6, 7, 9, 11, 13, 14, 20, 23, 25, 26, 27, 28, 32, 33, 36, 37, 40, 42, 48, 49, 50, 51, ...
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
OEIS Wiki, Centered polygonal numbers
Eric Weisstein's World of Mathematics, Centered Polygonal Number
MAPLE
select(isprime, [seq(11*k^2+11*k+1, k=1..1000)]);
MATHEMATICA
Intersection[Table[11 k^2 + 11 k + 1, {k, 0, 1000}], Prime[Range[13000]]]
Select[Table[11n^2+11n+1, {n, 150}], PrimeQ] (* Harvey P. Dale, Nov 22 2023 *)
PROG
(PARI) lista(nn) = for(n=1, nn, if(isprime(p=11*n^2 + 11*n + 1), print1(p, ", "))); \\ Altug Alkan, Aug 26 2016
(Magma) [k: n in [1..120] | IsPrime(k) where k is 11*n^2-11*n+1]; // Vincenzo Librandi, Aug 29 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 26 2016
STATUS
approved