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A076758
a(n) = n*(n+1)^2*(2+n)*(3+2*n)*(19+8*n)/180.
0
0, 9, 98, 516, 1870, 5369, 13132, 28560, 56772, 105105, 183678, 306020, 489762, 757393, 1137080, 1663552, 2379048, 3334329, 4589754, 6216420, 8297366, 10928841, 14221636, 18302480, 23315500, 29423745, 36810774, 45682308, 56267946, 68822945, 83630064
OFFSET
0,2
COMMENTS
Let M_n be the n X n matrix M_(i,j) = i^2-j^2. Then the characteristic polynomial of M_n is x^n+a(n-1)x^(n-2). - Benoit Cloitre, Nov 30 2002
FORMULA
G.f.: -x*(x^3+19*x^2+35*x+9)/(x-1)^7. [Colin Barker, Oct 22 2012]
a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7). - Wesley Ivan Hurt, May 24 2021
MATHEMATICA
Table[n (n+1)^2(2+n)(3+2n)(19+8n)/180, {n, 0, 30}] (* or *) LinearRecurrence[ {7, -21, 35, -35, 21, -7, 1}, {0, 9, 98, 516, 1870, 5369, 13132}, 40] (* Harvey P. Dale, Dec 19 2017 *)
CROSSREFS
Sequence in context: A123821 A145509 A098782 * A085868 A147637 A057933
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Nov 14 2002
STATUS
approved