OFFSET
1,2
COMMENTS
LINKS
Clark Kimberling, Antidiagonals n = 1..60, flattened
FORMULA
T(n,k) = 5*T(n,k-1) - 9*T(n,k-2) + 7*T(n,k-3) - 2*T(n,k-4).
G.f. for row n: f(x)/g(x), where f(x) = n^2 - (2*n^2 - 2*n - 1)*x + (n - 1)*x^2 and g(x) = (1 - 2*x)*(1 - x)^3.
T(n,k) = 2^k*(n^2 + 2*n + 3) - (n + k + 2)^2 + 2*(n + k + 1) - 1. - G. C. Greubel, Jul 25 2019
EXAMPLE
Northwest corner (the array is read by falling antidiagonals):
1, 6, 21, 58, 141, 318, ...
4, 17, 50, 125, 286, 621, ...
9, 34, 93, 222, 493, 1050, ...
16, 57, 150, 349, 762, 1605, ...
25, 86, 221, 506, 1093, 2286, ...
36, 121, 306, 693, 1486, 3093, ...
...
MATHEMATICA
(* First program *)
b[n_]:= 2^(n-1); c[n_]:= n^2;
T[n_, k_]:= Sum[b[k-i] c[n+i], {i, 0, k-1}]
TableForm[Table[T[n, k], {n, 1, 10}, {k, 1, 10}]]
Flatten[Table[T[n-k+1, k], {n, 12}, {k, n, 1, -1}]]
r[n_]:= Table[T[n, k], {k, 60}] (* A213573 *)
d = Table[T[n, n], {n, 40}] (* A213574 *)
s[n_]:= Sum[T[i, n+1-i], {i, 1, n}]
s1 = Table[s[n], {n, 1, 50}] (* A213575 *)
(* Additional programs *)
Table[2^(n-k+1)*((k+1)^2 +2)-((n+2)^2 +2), {n, 12}, {k, n}]//Flatten (* G. C. Greubel, Jul 25 2019 *)
PROG
(PARI) for(n=1, 12, for(k=1, n, print1(2^(n-k+1)*((k+1)^2 +2)-((n+2)^2 +2), ", "))) \\ G. C. Greubel, Jul 25 2019
(Magma) [2^(n-k+1)*((k+1)^2 +2)-((n+2)^2 +2): k in [1..n], n in [1..12]]; // G. C. Greubel, Jul 25 2019
(Sage) [[2^(n-k+1)*((k+1)^2 +2)-((n+2)^2 +2) for k in (1..n)] for n in (1..12)] # G. C. Greubel, Jul 25 2019
(GAP) Flat(List([1..12], n-> List([1..n], k-> 2^(n-k+1)*((k+1)^2 +2)- ((n+2)^2 +2) ))); # G. C. Greubel, Jul 25 2019
CROSSREFS
KEYWORD
AUTHOR
Clark Kimberling, Jun 18 2012
STATUS
approved