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A336182 a(n) = Sum_{k=0..n} (-3)^k * binomial(n,k)^3. 3

%I #22 Jul 13 2020 03:43:28

%S 1,-2,-14,136,106,-8492,35344,395008,-4547462,-4838372,365951356,

%T -1601617712,-19715085584,233866581856,285409397056,-20406741254144,

%U 90043530872218,1169513126877676,-13961261999882204,-18779832792734384,1270510266589738636,-5584024444211882792

%N a(n) = Sum_{k=0..n} (-3)^k * binomial(n,k)^3.

%C Diagonal of the rational function 1 / (1 + y + z + x*y + y*z - 3*z*x - 2*x*y*z).

%C Diagonal of the rational function 1 / ((1-x)*(1-y)*(1-z) + 3*x*y*z).

%H Robert Israel, <a href="/A336182/b336182.txt">Table of n, a(n) for n = 0..1020</a>

%F From _Robert Israel_, Jul 12 2020: (Start)

%F a(n) = hypergeom([-n,-n,-n],[1,1],3).

%F (24*n^3 + 176*n^2 + 416*n + 320)*a(n + 1) + (279*n^3 + 2325*n^2 + 6382*n + 5776)*a(n + 2) + (18*n^3 + 168*n^2 + 514*n + 512)*a(n + 3) + (3*n^3 + 31*n^2 + 104*n + 112)*a(n + 4)=0. (End)

%p f:= gfun:-rectoproc({(24*n^3 + 176*n^2 + 416*n + 320)*a(n + 1) + (279*n^3 + 2325*n^2 + 6382*n + 5776)*a(n + 2) + (18*n^3 + 168*n^2 + 514*n + 512)*a(n + 3) + (3*n^3 + 31*n^2 + 104*n + 112)*a(n + 4), a(0) = 1, a(1) = -2, a(2) = -14, a(3) = 136},a(n),remember):

%p map(f, [$0..30]); # _Robert Israel_, Jul 12 2020

%t a[n_] := Sum[(-3)^k * Binomial[n, k]^3, {k, 0, n}]; Array[a, 22, 0] (* _Amiram Eldar_, Jul 11 2020 *)

%o (PARI) {a(n) = sum(k=0, n, (-3)^k*binomial(n,k)^3)}

%Y Column k=3 of A336179.

%Y Cf. A206180.

%K sign

%O 0,2

%A _Seiichi Manyama_, Jul 10 2020

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Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)