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 A166378 #5 Jul 19 2019 14:25:54 %S A166378 1,0,1,2,0,1,0,6,0,1,12,0,12,0,1,0,60,0,20,0,1,150,0,180,0,30,0,1,0, %T A166378 1050,0,420,0,42,0,1,3416,0,4200,0,840,0,56,0,1,0,30744,0,12600,0, %U A166378 1512,0,72,0,1,124650,0,153720,0,31500,0,2520,0,90,0,1 %N A166378 Exponential Riordan array [1+x^2*sec(x), x]. %C A166378 Row sums are A166379. Diagonal sums are A166380. %F A166378 Number triangle T(n,k)=[k<=n]*A166377((n-k)/2)*C(n,k)*(1+(-1)^(n-k))/2. %e A166378 Triangle begins %e A166378 1, %e A166378 0, 1, %e A166378 2, 0, 1, %e A166378 0, 6, 0, 1, %e A166378 12, 0, 12, 0, 1, %e A166378 0, 60, 0, 20, 0, 1, %e A166378 150, 0, 180, 0, 30, 0, 1, %e A166378 0, 1050, 0, 420, 0, 42, 0, 1, %e A166378 3416, 0, 4200, 0, 840, 0, 56, 0, 1, %e A166378 0, 30744, 0, 12600, 0, 1512, 0, 72, 0, 1, %e A166378 124650, 0, 153720, 0, 31500, 0, 2520, 0, 90, 0, 1 %t A166378 (* The function RiordanArray is defined in A256893. *) %t A166378 RiordanArray[1 + #^2 Sec[#]&, #&, 11, True] // Flatten (* _Jean-François Alcover_, Jul 19 2019 *) %K A166378 easy,nonn,tabl %O A166378 0,4 %A A166378 _Paul Barry_, Oct 13 2009