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 A142719 #13 Dec 24 2018 21:41:31
%S A142719 41,41,43,47,53,61,71,83,97,113,131,151,173,197,223,251,281,313,347,
%T A142719 383,421,461,503,547,593,641,691,743,797,853,911,971,1033,1097,1163,
%U A142719 1231,1301,1373,1447,1523,1601,41,43,47,53,61,71,83,97,113,131,151,173,197
%N A142719 a(n) = if n < 41 then n^2 - n + 41, otherwise n^2 - 81*n + 1681.
%C A142719 A variation on Euler's prime generating polynomial found in a novel by Arthur C. Clarke and Gentry Lee. Gives 96 primes in first 100 terms.
%C A142719 Note that in n^2-81*n+1681, substitution of n= m+41 gives m^2+m+41, Euler's polynomial. So we get the same set of 40 primes twice.
%D A142719 Arthur C. Clarke and Gentry Lee, The Garden of Rama, Dell Publishing, 1991, ISBN 0-533-29817-8, page 59.
%H A142719 James Clewett and Brady Haran, <a href="https://www.youtube.com/watch?v=3K-12i0jclM">41 and more Ulam's Spiral</a>, Numberphile video, 2013.
%F A142719 a(n)=If[n < 41, n^2 - n + 41, n^2 - 81*n + 1681].
%t A142719 f[n_]=If[n<41,n^2-n+41,n^2-81*n+1681]; Table[f[n],{n,0,100}]
%Y A142719 Cf. A005846.
%K A142719 nonn
%O A142719 1,1
%A A142719 _Roger L. Bagula_, Sep 27 2008
%E A142719 Edited by _N. J. A. Sloane_, Sep 27 2008