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 A140643 #6 Dec 16 2014 05:36:32
%S A140643 1,1,1,1,1,2,2,1,1,4,4,1,1,2,8,8,2,1,1,4,16,16,4,1,1,2,8,32,32,8,2,1,
%T A140643 1,4,16,64,64,16,4,1
%N A140643 First differences of A140642.
%C A140643 (*) Main diagonal = A011782 but vertical = 1, A011782 unknown.
%F A140643 Also a triangle on line (*): 1; 1, 1; 1, 1, 2; 2, 1, 1, 4; 4, 1, 1, 2, 8; 8, 2, 1, 1, 4, 16; 16, 4, 1, 1, 2, 8, 32; 32, 8, 2, 1, 1, 4, 16, 64; Row sums:1, 2, 4, 8, 16 =A000079(n). Note even palindromes finishing a row and beginning next one.
%t A140643 maxTerm = 384; FixedPoint[(nMax++; Print["nMax = ", nMax]; jj = Table[(2^n - (-1)^n)/3, {n, 0, nMax}]; Table[Differences[jj, n], {n, 0, nMax}] // Flatten // Abs // Union // Select[#, 0 < # <= maxTerm &] &) &, nMax = 5 ] // Differences (* _Jean-François Alcover_, Dec 16 2014 *)
%K A140643 nonn,uned
%O A140643 0,6
%A A140643 _Paul Curtz_, Jul 08 2008