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 A126134 #6 Mar 30 2012 18:52:25 %S A126134 1,91,94,95,116,121,124,125,135,154,161,162,172,175,177,195,203,206, %T A126134 207,208,219,222,225,236,248,250,253,261,262,267,286,288,298,301,315, %U A126134 319,321,323,327,328,329,334,343,345,351,357,371,375,381,387,392,396,399 %N A126134 Nonprimes of the form r(r(r(r(r(r(r(n)+1)+1)+1)+1)+1)+1)+1, where A141468(n) = r(n) = n-th nonprime. %e A126134 If n = 1, then %e A126134 r(r(r(r(r(r(r(1)+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(0+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(0+1)+1)+1)+1)+1)+1 = r(r(r(r(r(1)+1)+1)+1)+1)+1 = r(r(r(r(0+1)+1)+1)+1)+1 = r(r(r(r(1)+1)+1)+1)+1 = r(r(r(0+1)+1)+1)+1 = r(r(r(1)+1)+1)+1 = r(r(0+1)+1)+1 = r(r(1)+1)+1 = r(0+1)+1 = r(1)+1 = 0+1 = 1 = a(1). %e A126134 If n = 2, then %e A126134 r(r(r(r(r(r(r(2)+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(1+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(2)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(1+1)+1)+1)+1)+1)+1 = r(r(r(r(r(2)+1)+1)+1)+1)+1 = r(r(r(r(1+1)+1)+1)+1)+1 = r(r(r(r(2)+1)+1)+1)+1 = r(r(r(1+1)+1)+1)+1 = r(r(r(2)+1)+1)+1 = r(r(1+1)+1)+1 = r(r(2)+1)+1 = r(1+1)+1 = r(2)+1 = 1+1 = 2 %e A126134 (prime). %e A126134 If n = 3, then %e A126134 r(r(r(r(r(r(r(3)+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(4+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(5)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(8+1)+1)+1)+1)+1)+1 = r(r(r(r(r(9)+1)+1)+1)+1)+1 = r(r(r(r(14+1)+1)+1)+1)+1 = r(r(r(r(15)+1)+1)+1)+1 = r(r(r(22+1)+1)+1)+1 = r(r(r(23)+1)+1)+1 = r(r(33+1)+1)+1 = r(r(34)+1)+1 = r(48+1)+1 = r(49)+1 = 66+1 = 67(prime). %e A126134 If n = 4, then %e A126134 r(r(r(r(r(r(r(4)+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(6+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(7)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(10+1)+1)+1)+1)+1)+1 = r(r(r(r(r(11)+1)+1)+1)+1)+1 = r(r(r(r(16+1)+1)+1)+1)+1 = r(r(r(r(17)+1)+1)+1)+1 = r(r(r(25+1)+1)+1)+1 = r(r(r(26)+1)+1)+1 = r(r(36+1)+1)+1 = r(r(37)+1)+1 = r(51+1)+1 = r(52)+1 = 70+1 = 71(prime). %e A126134 If n = 5, then %e A126134 r(r(r(r(r(r(r(5)+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(8+1)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(r(9)+1)+1)+1)+1)+1)+1 = r(r(r(r(r(14+1)+1)+1)+1)+1)+1 = r(r(r(r(r(15)+1)+1)+1)+1)+1 = r(r(r(r(22+1)+1)+1)+1)+1 = r(r(r(r(23)+1)+1)+1)+1 = r(r(r(33+1)+1)+1)+1 = r(r(r(34)+1)+1)+1 = r(r(48+1)+1)+1 = r(r(49)+1)+1 = r(66+1)+1 = r(67)+1 = 90+1 = 91 = a(2), %e A126134 etc. %Y A126134 Cf. A000040, A141468. %K A126134 nonn %O A126134 1,2 %A A126134 _Juri-Stepan Gerasimov_, Aug 25 2008 %E A126134 160 removed, 165 removed, 203 added, 261 added, etc. by _R. J. Mathar_, Sep 05 2008