A090448 Fourth column (m=3) of triangle A090447.
9, 96, 500, 1800, 5145, 12544, 27216, 54000, 99825, 174240, 290004, 463736, 716625, 1075200, 1572160, 2247264, 3148281, 4332000, 5865300, 7826280, 10305449, 13406976, 17250000, 21970000, 27720225, 34673184, 43022196, 52983000, 64795425, 78725120, 95065344
Offset: 3
Links
- Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).
Programs
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Maple
seq(mul(binomial(n,k),k=1..3),n=3..30); # Zerinvary Lajos, Dec 13 2007
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Mathematica
a[n_] := Product[Binomial[n, k], {k, 0, 3}]; Array[a, 30, 3] (* Amiram Eldar, Sep 08 2022 *) LinearRecurrence[{7,-21,35,-35,21,-7,1},{9,96,500,1800,5145,12544,27216},40] (* Harvey P. Dale, Jul 18 2025 *)
Formula
a(n) = A090447(n,3).
a(n) = (n^3*(n-1)^2*(n-2)^1)/(1!*2!*3!) for n >= 3.
From Colin Barker, Jan 21 2013: (Start)
a(n) = (n^6-4*n^5+5*n^4-2*n^3)/12.
G.f.: -x^3*(x^3+17*x^2+33*x+9)/(x-1)^7. (End)
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 04 2021
From Amiram Eldar, Sep 08 2022: (Start)
Sum_{n>=3} 1/a(n) = 207/4 - 9*Pi^2/2 - 6*zeta(3).
Sum_{n>=3} (-1)^(n+1)/a(n) = 165/4 - Pi^2/4 - 48*log(2) - 9*zeta(3)/2. (End)