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A011936 a(n) = floor( n(n-1)(n-2)(n-3)/26 ). 1

%I #11 Aug 02 2020 22:55:20

%S 0,0,0,0,0,4,13,32,64,116,193,304,456,660,924,1260,1680,2196,2824,

%T 3577,4472,5524,6752,8173,9808,11676,13800,16200,18900,21924,25296,

%U 29044,33193,37772,42808,48332,54373

%N a(n) = floor( n(n-1)(n-2)(n-3)/26 ).

%H <a href="/index/Rec#order_17">Index entries for linear recurrences with constant coefficients</a>, signature (4, -6, 4, -1, 0, 0, 0, 0, 0, 0, 0, 0, 1, -4, 6, -4, 1).

%F From _Chai Wah Wu_, Aug 02 2020: (Start)

%F a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + a(n-13) - 4*a(n-14) + 6*a(n-15) - 4*a(n-16) + a(n-17) for n > 16.

%F G.f.: x^5*(-4*x^10 + 3*x^9 - 4*x^8 + 2*x^7 - 4*x^6 + 2*x^5 - 4*x^4 + 2*x^3 - 4*x^2 + 3*x - 4)/(x^17 - 4*x^16 + 6*x^15 - 4*x^14 + x^13 - x^4 + 4*x^3 - 6*x^2 + 4*x - 1). (End)

%p A011936:=n->floor(n*(n-1)*(n-2)*(n-3)/26): seq(A011936(n), n=0..100); # _Wesley Ivan Hurt_, Feb 03 2017

%K nonn,easy

%O 0,6

%A _N. J. A. Sloane_

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Last modified March 28 08:12 EDT 2024. Contains 371236 sequences. (Running on oeis4.)