A011926 a(n) = floor(n*(n-1)*(n-2)*(n-3)/16).

0, 0, 0, 0, 1, 7, 22, 52, 105, 189, 315, 495, 742, 1072, 1501, 2047, 2730, 3570, 4590, 5814, 7267, 8977, 10972, 13282, 15939, 18975, 22425, 26325, 30712, 35626, 41107, 47197, 53940, 61380, 69564, 78540

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-6,6,-10,10,-5,1).

Programs

Magma

[Floor(n*(n-1)*(n-2)*(n-3)/16) : n in [0..100]]; // Wesley Ivan Hurt, Apr 20 2021

Mathematica

Table[Floor[(n(n-1)(n-2)(n-3))/16],{n,0,40}] (* or *) LinearRecurrence[{5,-10,10,-6,6,-10,10,-5,1},{0,0,0,0,1,7,22,52,105},40] (* Harvey P. Dale, Dec 16 2024 *)

Formula

From R. J. Mathar, Apr 15 2010: (Start)

G.f.: x^4*(x^4+1+2*x-3*x^2+2*x^3) / ((1-x)^5*(x^4+1) ).

a(n) = +5*a(n-1) -10*a(n-2) +10*a(n-3) -6*a(n-4) +6*a(n-5) -10*a(n-6) +10*a(n-7) -5*a(n-8) +a(n-9). (End)