OFFSET
1,2
FORMULA
a(n) = determinant of n X n matrix of first n^2 nonzero terms of A000217(k) for k>0. a(n) = determinant of n X n matrix of k*(k+1)/2 for k from 1 through n^2.
EXAMPLE
a(3) = -27 =
|.1..3..6|
|10.15.21|
|28.36.45|.
a(4) = 0 because of the singular matrix 0 =
|.1...3...6..10|
|15..21..28..36|
|45..55..66..78|
|91.105.120.136|.
MATHEMATICA
nmax = 100; Table[Det[Table[(k*(i-1) + j)*(k*(i-1) + j + 1)/2, {i, 1, k}, {j, 1, k}]], {k, 1, nmax}] (* Vaclav Kotesovec, Feb 24 2019 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Jonathan Vos Post, May 27 2006
EXTENSIONS
More terms from Vaclav Kotesovec, Feb 24 2019
STATUS
approved