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 A056887 #13 Apr 13 2020 11:43:21 %S A056887 1,0,-1,-2,1,2,7,-8,-7,-6,27,-54,57,-56,-233,-232,-7,-6,187,-588,1485, %T A056887 -1242,-6177,-3184,-639,640,-1441,-3472,13033,13032,-20745,-24120, %U A056887 1593,1594,20891,-60476,9069,-26964,-1916541,-6305202,1619109,-1599426,-8587701 %N A056887 Determinant of n X n Hankel matrix whose entries are t(i+j), 0 <= i, j < n, where t is the Thue-Morse sequence. %H A056887 Alois P. Heinz, <a href="/A056887/b056887.txt">Table of n, a(n) for n = 0..257</a> %o A056887 (PARI) a(n) = matdet(matrix(n, n, i, j, hammingweight(i+j-2) % 2)); \\ _Michel Marcus_, Apr 13 2020 %Y A056887 Cf. A010060. %K A056887 sign,look %O A056887 0,4 %A A056887 _Jeffrey Shallit_, Sep 04 2000 %E A056887 More terms from _Alois P. Heinz_, May 25 2013