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 A117947 #12 Feb 21 2024 08:19:02 %S A117947 1,1,1,1,-1,1,1,0,0,1,1,1,0,1,1,1,-1,1,1,-1,1,1,0,0,-1,0,0,1,1,1,0,-1, %T A117947 -1,0,1,1,1,-1,1,-1,1,-1,1,-1,1,1,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0, %U A117947 1,1,1,-1,1,0,0,0,0,0,0,1,-1,1,1,0,0,1,0,0,0,0,0,1,0,0,1,1,1,0,1,1,0,0,0,0,1,1,0,1,1,1,-1,1,1,-1,1,0,0,0,1,-1,1,1,-1,1 %N A117947 T(n,k)=L(C(n,k)/3) where L(j/p) is the Legendre symbol of j and p. %C A117947 Row sums are A059126. Diagonal sums are A117963. Could be called the Legendre-binomial matrix for p=3. %C A117947 The matrix square equals triangle A117939; the matrix log equals triangle A120854 divided by 2. - _Paul D. Hanna_, Jul 08 2006 %F A117947 T(n,k) = balanced ternary digit of C(n,k) mod 3. - _Paul D. Hanna_, Jul 08 2006 %e A117947 Triangle begins: %e A117947 1; %e A117947 1, 1; %e A117947 1, -1, 1; %e A117947 1, 0, 0, 1; %e A117947 1, 1, 0, 1, 1; %e A117947 ... %o A117947 (PARI) T(n,k)=(binomial(n,k)+1)%3-1 - _Paul D. Hanna_, Jul 08 2006 %Y A117947 Cf. A117939 (matrix square), A120854 (2*log). %K A117947 easy,sign,tabl %O A117947 0,1 %A A117947 _Paul Barry_, Apr 05 2006