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 A081999 #9 Aug 31 2018 16:50:36 %S A081999 1,2,7,9,29,31,71,73,143,149,229,233,359,361,485,487,629,631,821,823, %T A081999 1031,1033,1277,1279,1553,1559,1873,1877,2221,2237,2593,2599,2971, %U A081999 2999,3433,3449,3907,3911,4429,4441,4969,4973,5557,5561,6131,6133,6761,6763 %N A081999 First row of array in A081998. %H A081999 Charlie Neder, <a href="/A081999/b081999.txt">Table of n, a(n) for n = 0..140</a> %Y A081999 Cf. A081998, A082000, A082001. %K A081999 nonn %O A081999 0,2 %A A081999 _Amarnath Murthy_, Apr 05 2003 %E A081999 a(4)-a(47) from _Charlie Neder_, Aug 31 2018