A011921 [ n(n-1)(n-2)(n-3)/11 ].

0, 0, 0, 0, 2, 10, 32, 76, 152, 274, 458, 720, 1080, 1560, 2184, 2978, 3970, 5192, 6676, 8456, 10570, 13058, 15960, 19320, 23184, 27600, 32618, 38290, 44672, 51820, 59792, 68650, 78458, 89280, 101184

Offset

0,5

Links

Table of n, a(n) for n=0..34.

Index entries for linear recurrences with constant coefficients, signature (4, -6, 4, -1, 0, 0, 0, 0, 0, 0, 1, -4, 6, -4, 1).

Formula

a(n) = +4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +a(n-11) -4*a(n-12) +6*a(n-13) -4*a(n-14) +a(n-15). G.f.: 2*x^4*(1+x+2*x^2+x^4+2*x^5+x^6+2*x^8+x^9+x^10) / ( (1-x)^5*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10) ). - R. J. Mathar, Apr 15 2010

Mathematica

Table[Floor[(n(n-1)(n-2)(n-3))/11], {n, 0, 40}] (* or *) LinearRecurrence[ {4, -6, 4, -1, 0, 0, 0, 0, 0, 0, 1, -4, 6, -4, 1}, {0, 0, 0, 0, 2, 10, 32, 76, 152, 274, 458, 720, 1080, 1560, 2184}, 40] (* Harvey P. Dale, Oct 17 2012 *)

Prog

(PARI) a(n)=n*(n-1)*(n-2)*(n-3)\11 \\ Charles R Greathouse IV, Oct 18 2022

Crossrefs

Sequence in context: A050927 A197302 A263782 * A212714 A103290 A131068

Adjacent sequences: A011918 A011919 A011920 * A011922 A011923 A011924

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved