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 A104577 #7 Jun 14 2012 01:18:45
%S A104577 2,3,8,9,16,19,24,27,46,68,71,78,107,198,309,377,477,1057,1631,2419,
%T A104577 3974,4293,8247,10513,10709,12011,15042,30543,31607,39664,47552,145858
%N A104577 Indices of prime generalized tetranacci numbers, A073817.
%C A104577 The sequence of generalized tetranacci numbers is defined as beginning with 1, 3, 7, 15. Subsequent terms are the sum of the previous four terms. Note that the sequence of these generalized tetranacci numbers has many more primes than the tetranacci sequence A000078 (whose prime indices are in A104534).
%H A104577 Tony D. Noe and Jonathan Vos Post, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL8/Noe/noe5.html">Primes in Fibonacci n-step and Lucas n-step Sequences,</a> J. of Integer Sequences, Vol. 8 (2005), Article 05.4.4
%t A104577 a={-1, -1, -1, 4}; Do[s=Plus@@a; a=RotateLeft[a]; a[[4]]=s; If[PrimeQ[s], Print[n]], {n, 30000}]
%Y A104577 Cf. A104576 (indices of prime generalized tribonacci numbers).
%K A104577 nonn
%O A104577 1,1
%A A104577 _T. D. Noe_, Mar 16 2005