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 A292495 #46 Sep 26 2017 09:26:29 %S A292495 0,1,1,0,-2,-4,-1,-1,3,11,0,2,4,-2,-24,1,1,-3,-11,-7,41,0,-2,-4,2,24, %T A292495 38,-44,-1,-1,3,11,7,-41,-117,-29,0,2,4,-2,-24,-38,44,278,336,1,1,-3, %U A292495 -11,-7,41,117,29,-527,-1199,0,-2,-4,2,24,38,-44,-278,-336,718 %N A292495 Triangle read by rows: T(n,k) = (-2)*T(n-1,k-1) + T(n,k-1) with T(2*m,0) = 0 and T(2*m+1,0) = (-1)^m. %H A292495 Seiichi Manyama, <a href="/A292495/b292495.txt">Rows n = 0..139, flattened</a> %F A292495 T(n+1,n)^2 + T(n,n)^2 = 5^n. %e A292495 First few rows are: %e A292495 0; %e A292495 1, 1; %e A292495 0, -2, -4; %e A292495 -1, -1, 3, 11; %e A292495 0, 2, 4, -2, -24; %e A292495 1, 1, -3, -11, -7, 41; %e A292495 0, -2, -4, 2, 24, 38, -44; %e A292495 -1, -1, 3, 11, 7, -41, -117, -29; %e A292495 0, 2, 4, -2, -24, -38, 44, 278, 336. %Y A292495 The diagonal of the triangle is related to A099456. %Y A292495 The next diagonal of the triangle is related to A139011. %Y A292495 Cf. A006495, A006496. %Y A292495 T(n,k) = b*T(n-1,k-1) + T(n,k-1): A292789 (b=-3), this sequence (b=-2), A117918 and A228405 (b=1), A227418 (b=2), A292466 (b=4). %K A292495 sign,tabl,look %O A292495 0,5 %A A292495 _Seiichi Manyama_, Sep 22 2017