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 A132830 #4 Nov 21 2012 17:43:03
%S A132830 245,731,2189,19685,177149,531443,1594325,43046723,129140165,
%T A132830 387420491,1162261469,3486784403,10460353205,31381059611,94143178829,
%U A132830 847288609445,7625597484989,22876792454963,68630377364885,205891132094651
%N A132830 Numbers of the form 3^n+2 which are not primes.
%H A132830 Harvey P. Dale, <a href="/A132830/b132830.txt">Table of n, a(n) for n = 1..1000</a>
%t A132830 a = {}; c = 3^x + 2; Do[If[PrimeQ[c],0, AppendTo[a, c]], {x, 0, 100}]; a (*Artur Jasinski*)
%t A132830 Select[3^Range[0,30]+2,!PrimeQ[#]&] (* _Harvey P. Dale_, Nov 21 2012 *)
%Y A132830 Cf. A057735, A051783, A132829.
%K A132830 nonn
%O A132830 1,1
%A A132830 _Artur Jasinski_, Sep 03 2007