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 A248921 #10 Nov 30 2019 13:27:18
%S A248921 5,17,977,28697,56417,1428864769,2809074173,21344178433,626815657409,
%T A248921 18407729752001,
%U A248921 2317881588988297338942875602391948125494800020122167809,136507010958920295813169620935932629930648432530102206331972221346174230852977164801
%N A248921 Primes in the pentanacci numbers sequence A000322.
%C A248921 a(13) is too large to display here. It has 132 digits and is the 450th term in A000322.
%H A248921 Harvey P. Dale, <a href="/A248921/b248921.txt">Table of n, a(n) for n = 1..19</a>
%t A248921 a={1,1,1,1,1}; For[n=5, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[5]]=sum]
%t A248921 Select[With[{c={1,1,1,1,1}},LinearRecurrence[c,c,300]],PrimeQ] (* _Harvey P. Dale_, Nov 30 2019 *)
%Y A248921 Cf. A001590, A001631, A100683, A231574, A231575, A232543, A214899, A020992, A233554, A214727, A234696, A141523, A235862, A214825, A235873, A001630, A241660, A247027, A000288, A247561, A000322, A248920.
%K A248921 nonn
%O A248921 1,1
%A A248921 _Robert Price_, Oct 16 2014