This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A264821 #10 Feb 16 2025 08:33:27
%S A264821 43,211,631,1093,1471,2143,4201,6091,7393,8821,17851,23143,24781,
%T A264821 25621,33811,36793,38851,39901,42043,45361,53593,57331,63841,76441,
%U A264821 91771,96643,99961,101641,110251,126631,128521,138181,146161,152293,158551,184843,189421,220543
%N A264821 Centered 14-gonal (or tetradecagonal) primes.
%C A264821 Primes of the form 7*k^2 - 7*k + 1.
%H A264821 OEIS Wiki, <a href="https://oeis.org/wiki/Figurate_numbers">Figurate numbers</a>
%H A264821 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CenteredPolygonalNumber.html">Centered Polygonal Number</a>
%H A264821 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PrimeNumber.html">Prime Number</a>
%t A264821 Select[Table[7n^2-7n+1,{n,200}],PrimeQ] (* _Harvey P. Dale_, Jul 27 2021 *)
%o A264821 (PARI) for(n=1, 1e3, if(isprime(k=7*n^2-7*n+1), print1(k,", "))) \\ _Altug Alkan_, Nov 26 2015
%Y A264821 Cf. A069127, A000040.
%K A264821 nonn
%O A264821 1,1
%A A264821 _Ilya Gutkovskiy_, Nov 26 2015