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 A179899 #8 Feb 10 2019 01:50:54 %S A179899 0,12,21,30,36,39,48,51,57,66,72,75,81,84,93,96,102,111,114,120,126, %T A179899 129,135,138,141,147,156,165,171,174,177,180,183,186,192,198,201,210, %U A179899 213,216,219,228,231,237,240,246,252,255,261,264,273,276,279,282,291 %N A179899 Integers of the form A179896(n)/A141468(n+1). %H A179899 Nathaniel Johnston, <a href="/A179899/b179899.txt">Table of n, a(n) for n = 1..10000</a> %e A179899 0 = 0/1, 12 = 108/9, 21 = 315/15, 30 = 630/21, 36 = 900/25 and so on. %p A179899 ithnonprime := proc(n)local k: option remember: if(n=1)then return 1: else k := procname(n-1)+1: while true do if(not isprime(k))then return k fi: k:=k+1: od: fi: end: A179899ind := proc(n) option remember: local k: if(n=1)then return 1:fi: for k from procname(n-1)+1 do if(ithnonprime(k) mod 2 <> 0)then return k: fi: od: end: A179899 := proc(n) return 3*(ithnonprime(A179899ind(n))-1)/2: end: seq(A179899(n),n=1..55); # _Nathaniel Johnston_, May 05 2011 %Y A179899 Cf. A000040, A179545, A179896. %K A179899 easy,nonn %O A179899 1,2 %A A179899 _Odimar Fabeny_, Jul 31 2010 %E A179899 More terms from _Odimar Fabeny_, Aug 12 2010 %E A179899 Definition rephrased by _R. J. Mathar_, Sep 01 2010