OFFSET
1,2
COMMENTS
T(n, k) is the k-th super- and subdiagonal sum of the Hankel matrix M(n) whose permanent is A374668(n).
FORMULA
O.g.f.: x*(1 - 4*x^8*y^5 + x*(11 + 2*y) - x^7*y^4*(7 + 16*y) - x^2*(-11 + 6*y - 6*y^2) - x^5*y^2*(2 - 46*y - 3*y^2) - x^6*y^3*(-2 - 27*y + 4*y^2) - x^3*(-1 + 18*y + 38*y^2 - 2*y^3) - x^4*y*(2 + 14*y + 2*y^2 - y^3))/((1 - x)^5*(1 - x*y)^4*(1 + x*y)^2).
T(n,2) = A123865(n-1) for n > 1.
EXAMPLE
n\k| 0 1 2 3 4 5
---+------------------------------
1 | 1
2 | 16 4
3 | 81 36 15
4 | 256 144 80 32
5 | 625 400 255 140 65
6 | 1296 900 624 396 240 108
...
For n = 3 the matrix M is
[ 1, 4, 15]
[ 4, 15, 32]
[15, 32, 65]
and therefore T(3, 0) = 1 + 15 + 65 = 81, T(3, 1) = 4 + 32 = 36, and T(3, 2) = 15.
MATHEMATICA
T[n_, k_]:=(n-k)*n*(4*n^2 - 4*n*k+2*k^2-1+(-1)^k)/4; Table[T[n, k], {n, 10}, {k, 0, n-1}]//Flatten
CROSSREFS
KEYWORD
AUTHOR
Stefano Spezia, Jul 17 2024
STATUS
approved