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 A162438 #11 Aug 02 2015 02:08:15
%S A162438 1,2,6,26,218,7002,1792858,14687099738,30801080592587610,
%T A162438 529158535306496354546309978,
%U A162438 19064945459410035469668296404984822042942298
%N A162438 a(1)=1, a(2)=2. Take terms a(n-1) and a(n-2), then convert to binary. Concatenate them, with either binary a(n-1) on the left and a(n-2) on the right, or with a(n-1) on the right and a(n-2) on the left such that the value of the resulting binary number is maximized. a(n) = the decimal equivalent of the resulting binary number.
%C A162438 The difference between A162438(n) - A162437(n): 0, 0, 1, 5, 45, 1453, 372141, 3048582573, ..., . - _Robert G. Wilson v_, Jul 27 2009
%e A162438 The binary representation of the first few terms: 1, 10, 110, 11010, 11011010.
%t A162438 a[1] = 1; a[2] = 2; a[n_] := Block[ {a1 = IntegerDigits[a[n - 1], 2], a2 = IntegerDigits[ a[n - 2], 2]}, Max[ FromDigits[ Join[a1, a2], 2], FromDigits[ Join[a2, a1], 2]]]; Array[a, 13] (* _Robert G. Wilson v_, Jul 27 2009 *)
%Y A162438 Cf. A005203, A111061, A162437.
%K A162438 base,nonn
%O A162438 1,2
%A A162438 _Leroy Quet_, Jul 03 2009
%E A162438 More terms from _Robert G. Wilson v_, Jul 27 2009