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

Author

Ilya Gutkovskiy, Nov 26 2015

Keywords

• nonn

Comments

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

Links

• OEIS Wiki, Figurate numbers
• Eric Weisstein's World of Mathematics, Centered Polygonal Number
• Eric Weisstein's World of Mathematics, Prime Number

Crossrefs

Cf. A069131, A000040.

Programs

PARI

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