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 A268494 #6 Feb 10 2016 15:43:35
%S A268494 0,2,4,12,13,14,21,44,69,76,107,109,114,127,204,214,246,249,298,317,
%T A268494 394,402,420,440,442,477,504,508,533,550,552,610,632,647,656,682,743,
%U A268494 745,801,808,925,943,952,954,961,966,980,1010,1050,1089,1112,1162,1167,1200,1229,1233,1244,1389,1401,1415,1423,1432,1462
%N A268494 Indices n of "late birds" (a(n)<a(k) for all k>n) in A268630 (= a(n)^2+a(n+1) is prime).
%C A268494 See A268495 for the corresponding values. We use offset 0 here because the first term has a special status (it's not really "late") and also because all related sequences (A268630 and A268494 - A268497) have a(0)=0 and omitting this term yields the corresponding "positive integer" variant.
%C A268494 Assuming that A268630 is a permutation of the nonnegative integers N (as conjectured), the characterization given in the name is equivalent to say that a(n) equals the least number not occurring earlier. The sequence defined that way is finite if and only if A268630 is not a permutation of N.
%H A268494 M. F. Hasler, <a href="/A268494/b268494.txt">Table of n, a(n) for n = 0..428</a>
%o A268494 (PARI) show(n,a=0,u=[a-1])={for(n=1, n, a==u[1]+1&&print1(n-1","); u=setunion(u,[a]); while(#u>1&&u[2]==u[1]+1,u=u[^1]); for(k=u[1]+1, 9e9, !setsearch(u, k) && isprime(a*a+k) && (a=k) && break))}
%K A268494 nonn
%O A268494 0,2
%A A268494 _M. F. Hasler_, Feb 09 2016