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 A337064 #15 Sep 18 2020 13:33:03
%S A337064 0,3,5,2,16,20,30,40,9,23,90,57,110,29,36,12,220,33,342,230,163,179,
%T A337064 494,19,15,109,128,88,694,82,744,43,125,219,169,72,1060,373,253,85,
%U A337064 1205,113,1346,151,207,564,1726,131,75,332
%N A337064 a(n) is the index of the first occurrence of n in A337063, or -1 if n never appears.
%C A337064 419 is the lowest number that does not appear in the first 100000 terms of A337063.
%H A337064 Rémy Sigrist, <a href="/A337064/b337064.txt">Table of n, a(n) for n = 1..10000</a>
%H A337064 Rémy Sigrist, <a href="/A337064/a337064.gp.txt">PARI program for A337064</a>
%e A337064 A337063 starts {1, 1, 4, 2, ...} so a(2) = 3.
%o A337064 (PARI) See Links section.
%Y A337064 Cf. A337063, A316774 (adds the two previous terms), A316973 (similar index for the addition sequence).
%K A337064 nonn
%O A337064 1,2
%A A337064 _Alex Lauber_, Aug 13 2020