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 A090562 #38 Sep 08 2022 08:45:12 %S A090562 11,31,61,101,151,211,281,661,911,1051,1201,1361,1531,1901,2311,2531, %T A090562 3001,3251,3511,4651,5281,6301,6661,7411,9461,9901,12251,13781,14851, %U A090562 15401,18301,18911,19531,20161,22111,24151,24851,25561,27011,27751 %N A090562 Primes of the form 5k^2 + 5k + 1. %C A090562 Or, primes obtained as a concatenation of a triangular number and 1. %C A090562 Centered decagonal primes. - _Paul Muljadi_, Oct 04 2005 %H A090562 Vincenzo Librandi, <a href="/A090562/b090562.txt">Table of n, a(n) for n = 1..5000</a> %H A090562 Wikipedia, <a href="http://en.wikipedia.org/wiki/Centered_decagonal_number">Centered decagonal number.</a> %t A090562 Select[5(#^2 - #) + 1 & /@ Range[75], PrimeQ[ # ] &] (* _Robert G. Wilson v_, Oct 10 2005 *) %o A090562 (Magma) [a: n in [0..100] | IsPrime(a) where a is 5*n^2 + 5*n + 1]; // _Vincenzo Librandi_, Dec 13 2011 %Y A090562 Cf. A090563, A062786. %K A090562 easy,nonn %O A090562 1,1 %A A090562 _Amarnath Murthy_, Dec 11 2003 %E A090562 Edited and extended by _Robert G. Wilson v_, Oct 10 2005