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 A213752 #4 Jun 22 2012 13:46:14 %S A213752 1,6,3,19,14,5,44,37,22,7,85,76,55,30,9,146,135,108,73,38,11,231,218, %T A213752 185,140,91,46,13,344,329,290,235,172,109,54,15,489,472,427,362,285, %U A213752 204,127,62,17,670,651,600,525,434,335,236,145,70,19,891,870,813 %N A213752 Rectangular array: (row n) = b**c, where b(h) = 2*h-1, c(h) = b(n-1+h), n>=1, h>=1, and ** = convolution. %C A213752 Principal diagonal: A100157 %C A213752 Antidiagonal sums: A071238 %C A213752 row 1, (1,3,5,7,9,...)**(1,3,5,7,9,...): A005900 %C A213752 row 2, (1,3,5,7,9,...)**(3,5,7,9,11,...): A143941 %C A213752 row 3, (1,3,5,7,9,...)**(5,7,9,11,13,...): (2*k^3 + 12*k^2 + k)/6 %C A213752 row 4, (1,3,5,7,9,...)**(7,9,11,13,15,,...): (2*k^3 + 18*k^2 + k)/6 %C A213752 For a guide to related arrays, see A213500. %F A213752 T(n,k) = 4*T(n,k-1)-6*T(n,k-2)+4*T(n,k-3)-T(n,k-4). %F A213752 G.f. for row n: f(x)/g(x), where f(x) = 2*n - 1 + 2*x - (2*n - 3)*x^2 and g(x) = (1 - x )^4. %e A213752 Northwest corner (the array is read by falling antidiagonals): %e A213752 1...6....19...44....85....146 %e A213752 3...14...37...76....135...218 %e A213752 5...22...55...108...185...290 %e A213752 7...30...73...140...235...362 %e A213752 9...38...91...172...285...434 %t A213752 b[n_] := 2 n - 1; c[n_] := 2 n - 1; %t A213752 t[n_, k_] := Sum[b[k - i] c[n + i], {i, 0, k - 1}] %t A213752 TableForm[Table[t[n, k], {n, 1, 10}, {k, 1, 10}]] %t A213752 Flatten[Table[t[n - k + 1, k], {n, 12}, {k, n, 1, -1}]] %t A213752 r[n_] := Table[t[n, k], {k, 1, 60}] (* A213752 *) %t A213752 Table[t[n, n], {n, 1, 40}] (* A100157 *) %t A213752 s[n_] := Sum[t[i, n + 1 - i], {i, 1, n}] %t A213752 Table[s[n], {n, 1, 50}] (* A071238 *) %Y A213752 Cf. A213500. %K A213752 nonn,tabl,easy %O A213752 1,2 %A A213752 _Clark Kimberling_, Jun 20 2012