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 A124846 #8 Nov 11 2019 21:49:20 %S A124846 1,1,3,1,6,1,1,9,3,3,1,12,6,12,1,1,15,10,30,5,3,1,18,15,60,15,18,1,1, %T A124846 21,21,105,35,63,7,3,1,24,28,168,70,168,28,24,1,1,27,36,252,126,378, %U A124846 84,108,9,3,1,30,45,360,210,756,210,360,45,30,1,1,33,55,495,330,1386,462,990 %N A124846 Triangle read by rows: T(n,k) = (2 - (-1)^k)*binomial(n,k) (0 <= k <= n). %e A124846 First few rows of the triangle: %e A124846 1; %e A124846 1, 3; %e A124846 1, 6, 1; %e A124846 1, 9, 3, 3; %e A124846 1, 12, 6, 12, 1; %e A124846 1, 15, 10, 30, 5, 3; %e A124846 ... %e A124846 A046055(4) = 16 = sum of row 4 terms (1 + 9 + 3 + 3). %p A124846 T:=(n,k)->(2-(-1)^k)*binomial(n,k): for n from 0 to 12 do seq(T(n,k),k=0..n) od; # yields sequence in triangular form %Y A124846 Cf. A010684, A046055, A124845. %K A124846 nonn,tabl %O A124846 0,3 %A A124846 _Gary W. Adamson_, Nov 10 2006 %E A124846 Edited by _N. J. A. Sloane_, Nov 24 2006