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%I #10 Nov 26 2015 08:43:57
%S 19,109,181,271,379,811,991,2161,3079,4159,4969,5851,7309,8929,10099,
%T 10711,13339,17029,21169,22051,23869,25759,26731,28729,32941,34039,
%U 37441,38611,39799,48619,58321,59779,67339,70489,72091,89101,90901,102079,109891,117991,122149
%N Centered 18-gonal (or octadecagonal) primes.
%C Primes of the form 9*k^2 - 9*k + 1.
%H OEIS Wiki, <a href="https://oeis.org/wiki/Figurate_numbers">Figurate numbers</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CenteredPolygonalNumber.html">Centered Polygonal Number</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PrimeNumber.html">Prime Number</a>
%o (PARI) for(n=1, 1e3, if(isprime(k=9*n^2-9*n+1), print1(k,", "))) \\ _Altug Alkan_, Nov 26 2015
%Y Cf. A069131, A000040.
%K nonn
%O 1,1
%A _Ilya Gutkovskiy_, Nov 26 2015
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