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 A233190 #12 Dec 07 2013 13:00:24
%S A233190 0,2,3,9,13,27,35,39,87,95,97,99,113,131,233,971,3851,5637,6553,106099
%N A233190 Indices of primes in the tribonacci-like sequence, A214899.
%C A233190 a(21) > 2*10^5.
%t A233190 a={2,1,2};Print[1],Print[2];For[n=3,n<=1000,n++,sum=Plus@@a;If[PrimeQ[sum],Print[n]];a=RotateLeft[a]; a[[3]]=sum]
%Y A233190 Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607.
%K A233190 nonn
%O A233190 1,2
%A A233190 _Robert Price_, Dec 05 2013