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 A071859 #9 Mar 31 2012 13:22:26 %S A071859 0,0,-1,1,1,-1,0,0,1,1,-1,-1,0,0,-1,1,1,1,-2,2,3,-3,-1,1,-2,-2,1,1,1, %T A071859 -1,0,0,1,1,-1,1,2,-2,-1,-1,3,3,-2,-2,-1,1,-1,-1,0,0,1,-1,-1,1,0,0,1, %U A071859 1,-1,-1,0,0,-1,1,1,1,-2,2,3,-3,-1,-1,4,4,-3,-3 %N A071859 Determinant of M_n where M_n is the n X n matrix m_(i,j) = A030300(i+j). %C A071859 a(n)=0 for n=1,2,7,8,13,14,31,32,49,50,55,56,61,62...hence if a(n)=0, n odd it seems that a(n+1)=0. It seems also that if a(n)=0 (n odd ) then n == 1 mod 6 (converse doesn't hold). %o A071859 (PARI) for(n=1,70,print1(matdet(matrix(n,n,i,j,length(binary(j+i))%2)),",")) %Y A071859 Cf. A030300. %K A071859 easy,sign %O A071859 1,19 %A A071859 _Benoit Cloitre_, Jun 09 2002 %E A071859 Name corrected by _Nathaniel Johnston_, Sep 26 2011