A011901 [ n(n-1)(n-2)/19 ].

0, 0, 0, 0, 1, 3, 6, 11, 17, 26, 37, 52, 69, 90, 114, 143, 176, 214, 257, 306, 360, 420, 486, 559, 639, 726, 821, 923, 1034, 1153, 1282, 1419, 1566, 1722, 1889, 2066, 2254, 2453, 2664, 2886, 3120, 3366, 3625, 3897, 4182, 4481, 4793, 5120, 5461, 5818, 6189

Offset

0,6

Links

Table of n, a(n) for n=0..50.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,-3,3,-1).

Formula

a(n) = +3*a(n-1) -3*a(n-2) +a(n-3) +a(n-19) -3*a(n-20) +3*a(n-21) -a(n-22). - R. J. Mathar, Apr 15 2010

G.f.: (x^4 (1+x^4) (1+x^3 (1-x+x^3+x^6) (1+(-1+x) x (1+x^2))))/(1+x (-3+x (3+x (-1+(-1+x)^3 x^16)))). - Peter J. C. Moses, Jun 02 2014

Mathematica

Table[Floor[n(n-1)(n-2)/19], {n, 0, 50}] (* or  *) LinearRecurrence[{3, -3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -3, 3, -1}, {0, 0, 0, 0, 1, 3, 6, 11, 17, 26, 37, 52, 69, 90, 114, 143, 176, 214, 257, 306, 360, 420}, 50] (* Harvey P. Dale, May 30 2021 *)

Prog

(PARI) a(n)=n*(n-1)*(n-2)\19 \\ Charles R Greathouse IV, Oct 21 2022

Crossrefs

Sequence in context: A107957 A000603 A003453 * A169739 A109471 A279032

Adjacent sequences: A011898 A011899 A011900 * A011902 A011903 A011904

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved