A264825 Centered 18-gonal (or octadecagonal) primes.

19, 109, 181, 271, 379, 811, 991, 2161, 3079, 4159, 4969, 5851, 7309, 8929, 10099, 10711, 13339, 17029, 21169, 22051, 23869, 25759, 26731, 28729, 32941, 34039, 37441, 38611, 39799, 48619, 58321, 59779, 67339, 70489, 72091, 89101, 90901, 102079, 109891, 117991, 122149

Offset

1,1

Comments

Primes of the form 9*k^2 - 9*k + 1.

Links

Table of n, a(n) for n=1..41.

OEIS Wiki, Figurate numbers

Eric Weisstein's World of Mathematics, Centered Polygonal Number

Eric Weisstein's World of Mathematics, Prime Number

Prog

(PARI) for(n=1, 1e3, if(isprime(k=9*n^2-9*n+1), print1(k, ", "))) \\ Altug Alkan, Nov 26 2015

Crossrefs

Cf. A069131, A000040.

Sequence in context: A238108 A129081 A282324 * A142322 A306855 A243761

Adjacent sequences: A264822 A264823 A264824 * A264826 A264827 A264828

Keyword

nonn

Author

Ilya Gutkovskiy, Nov 26 2015

Status

approved