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A011931 a(n) = floor(n*(n-1)*(n-2)*(n-3)/21). 0

%I #17 Jun 19 2022 03:33:09

%S 0,0,0,0,1,5,17,40,80,144,240,377,565,817,1144,1560,2080,2720,3497,

%T 4429,5537,6840,8360,10120,12144,14457,17085,20057,23400,27144,31320,

%U 35960,41097,46765,53001,59840,67320,75480,84360,94001,104445,115737,127920,141040,155144,170280,186497,203845,222377,242144

%N a(n) = floor(n*(n-1)*(n-2)*(n-3)/21).

%H <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1,0,0,1,-4,6,-4,1).

%F 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). [_R. J. Mathar_, Apr 15 2010]

%t Table[Floor[n (n - 1) (n - 2) (n - 3)/21], {n, 0, 30}] (* _Wesley Ivan Hurt_, Jun 18 2022 *)

%K nonn,easy

%O 0,6

%A _N. J. A. Sloane_

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Last modified February 28 21:38 EST 2024. Contains 370400 sequences. (Running on oeis4.)