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 A106849 #1 Jul 19 2005 03:00:00 %S A106849 2,17,19,23,29,47,59,61,97,109,113,131,149,167,179,181,193,223,229, %T A106849 233,257,263,269,313,337,367,379,383,389,419,433,461,487,491,499,503, %U A106849 509,541,571,577,593,619,647,659,701,709,727,743,811,821,823,857,863,887 %N A106849 Values of n for which A106848(n) = n-1. %e A106849 a(2) = 17 because A106848(17) = 16. %Y A106849 Cf. A106848. %K A106849 base,nonn %O A106849 1,1 %A A106849 Chuck Seggelin (seqfan(AT)plastereddragon.com), May 08 2005