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A011917 [ n(n-1)(n-2)(n-3)/7 ]. 1
0, 0, 0, 0, 3, 17, 51, 120, 240, 432, 720, 1131, 1697, 2451, 3432, 4680, 6240, 8160, 10491, 13289, 16611, 20520, 25080, 30360, 36432, 43371, 51257, 60171, 70200, 81432, 93960, 107880, 123291, 140297, 159003 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,5
LINKS
FORMULA
a(n) = +4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +a(n-7) -4*a(n-8) +6*a(n-9) -4*a(n-10) +a(n-11). G.f.: x^4*(3+5*x+x^2+6*x^3+x^4+5*x^5+3*x^6) / ( (1-x)^5*(1+x+x^2+x^3+x^4+x^5+x^6) ). - R. J. Mathar, Apr 15 2010
MATHEMATICA
Table[Floor[Times@@(n-Range[0, 3])/7], {n, 0, 40}] (* or *) LinearRecurrence[ {4, -6, 4, -1, 0, 0, 1, -4, 6, -4, 1}, {0, 0, 0, 0, 3, 17, 51, 120, 240, 432, 720}, 50] (* Harvey P. Dale, Oct 20 2016 *)
PROG
(PARI) a(n)=n*(n-1)*(n-2)*(n-3)\7 \\ Charles R Greathouse IV, Oct 18 2022
CROSSREFS
Sequence in context: A297514 A307862 A132124 * A018691 A332869 A225727
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified April 12 12:48 EDT 2024. Contains 371635 sequences. (Running on oeis4.)