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

0, 0, 0, 0, 0, 4, 13, 32, 64, 116, 193, 304, 456, 660, 924, 1260, 1680, 2196, 2824, 3577, 4472, 5524, 6752, 8173, 9808, 11676, 13800, 16200, 18900, 21924, 25296, 29044, 33193, 37772, 42808, 48332, 54373

Offset

0,6

Links

Table of n, a(n) for n=0..36.

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

Formula

From Chai Wah Wu, Aug 02 2020: (Start)

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.

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)

Maple

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

Crossrefs

Sequence in context: A036487 A184632 A212747 * A037235 A363256 A051912

Adjacent sequences: A011933 A011934 A011935 * A011937 A011938 A011939

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved