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 A087740 #15 Aug 29 2017 00:06:39
%S A087740 1,1,1,2,1,2,1,1,2,1,2,2,2,2,2,1,1,2,2,2,2,2,2,1,3,3,3,2,2,2,4,1,2,2,
%T A087740 2,2,1,2,1,2,3,3,1,1,1,3,3,1,3,2,1,1,2,1,5,5,5,5,2,2,2,2,7,1,2,2,3,3,
%U A087740 3,2,2,1,2,2,1,2,1,2,1,2,3,2,2,6,7,7,4,3,4,4,2,2,2,4,4,3,7,3,3,2,6,3,1,2,3,1,3,2,1,3,1,1,3,1,3,2,9,5,9,10
%N A087740 a(n) = 1 + abs(A004001(A005185(n)) - A005185(A004001(n))).
%C A087740 A "commutator" between the Hofstadter A005185 sequence and the Conway-Hofstadter A004001 sequence.
%H A087740 Antti Karttunen, <a href="/A087740/b087740.txt">Table of n, a(n) for n = 1..100000</a>
%t A087740 Conway[n_Integer?Positive] := Conway[n] =Conway[Conway[n-1]] + Conway[n - Conway[n-1]] Conway[1] = Conway[2] = 1 Hofstadter[n_Integer?Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n-1]] + Hofstadter[n - Hofstadter[n-2]] Hofstadter[1] = Hofstadter[2] = 1 digits=200 a=Table[1+Abs[Conway[Hofstadter[n]]-Hofstadter[Conway[n]]], {n, 1, digits}]
%o A087740 (Scheme) (define (A087740 n) (+ 1 (abs (- (A004001 (A005185 n)) (A005185 (A004001 n)))))) ;; Scheme-code for A004001 and A005185 given under those entries.
%Y A087740 Cf. A004001, A005185, A284019 (compare the scatter plots).
%Y A087740 Cf. also A286560.
%K A087740 nonn,look
%O A087740 1,4
%A A087740 _Roger L. Bagula_, Oct 01 2003
%E A087740 Data section extended to 120 terms by _Antti Karttunen_, May 22 2017