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 A213564 #9 Jul 12 2012 12:23:20 %S A213564 1,7,4,27,21,9,77,67,43,16,182,167,127,73,25,378,357,297,207,111,36, %T A213564 714,686,602,467,307,157,49,1254,1218,1106,917,677,427,211,64,2079, %U A213564 2034,1890,1638,1302,927,567,273,81,3289,3234,3054,2730,2282,1757 %N A213564 Rectangular array: (row n) = b**c, where b(h) = h*(h+1)/2, c(h) = (n-1+h)^2, n>=1, h>=1, and ** = convolution. %C A213564 Principal diagonal: A213565 %C A213564 Antidiagonal sums: A101094 %C A213564 Row 1, (1,3,6,...)**(1,4,9,...): A005585 %C A213564 Row 2, (1,3,6,...)**(4,9,16,...): (k^5 +25*k^4 + 60*k^3 + 215*k^2 + 59*k)/60 %C A213564 Row 3, (1,3,6,...)**(9,16,25,...): (k^5 +35*k^4 + 30*k^3 + 505*k^2 + 149*k)/60 %C A213564 For a guide to related arrays, see A213500. %H A213564 Clark Kimberling, <a href="/A213564/b213564.txt">Antidiagonals n = 1..60, flattened</a> %F A213564 T(n,k) = 6*T(n,k-1) - 15*T(n,k-2) + 20*T(n,k-3) - 15*T(n,k-4) + 6*T(n,k-5) - T(n,k-6). %F A213564 G.f. for row n: f(x)/g(x), where f(x) = n^2 - (2*n^2 - 2n - 1)*x + ((n - 1)^2)*x^2 and g(x) = (1 - x)^6. %e A213564 Northwest corner (the array is read by falling antidiagonals): %e A213564 1....7.....27....77....182 %e A213564 4....21....67....167...357 %e A213564 9....43....127...297...602 %e A213564 16...73....207...467...917 %e A213564 25...111...307...677...1302 %e A213564 36...157...427...927...1757 %t A213564 b[n_] := n (n + 1)/2; c[n_] := n^2 %t A213564 t[n_, k_] := Sum[b[k - i] c[n + i], {i, 0, k - 1}] %t A213564 TableForm[Table[t[n, k], {n, 1, 10}, {k, 1, 10}]] %t A213564 Flatten[Table[t[n - k + 1, k], {n, 12}, {k, n, 1, -1}]] %t A213564 r[n_] := Table[t[n, k], {k, 1, 60}] (* A213564 *) %t A213564 d = Table[t[n, n], {n, 1, 40}] (* A213565 *) %t A213564 s[n_] := Sum[t[i, n + 1 - i], {i, 1, n}] %t A213564 s1 = Table[s[n], {n, 1, 50}] (* A101094 *) %Y A213564 Cf. A213500. %K A213564 nonn,tabl,easy %O A213564 1,2 %A A213564 _Clark Kimberling_, Jun 18 2012