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A053618 a(n) = ceiling(C(n,4)/n). 6
0, 0, 0, 1, 1, 3, 5, 9, 14, 21, 30, 42, 55, 72, 91, 114, 140, 170, 204, 243, 285, 333, 385, 443, 506, 575, 650, 732, 819, 914, 1015, 1124, 1240, 1364, 1496, 1637, 1785, 1943, 2109, 2285, 2470, 2665, 2870, 3086, 3311, 3548, 3795, 4054, 4324 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

R. L. Graham and N. J. A. Sloane, Lower bounds for constant weight codes, IEEE Trans. Inform. Theory, 26 (1980), 37-43.

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

FORMULA

a(n) = ( 2*n^3 - 12*n^2 + 22*n - 3 + 9*(-1)^n + 3*(1+(-1)^n)*(-1)^(n*(n-1)/2) - 6*(1 + (-1)^n)*(-1)^floor(n/4) )/48. - Luce ETIENNE, Jan 20 2015

G.f.: x^4*(x^2 - x + 1)*(x^4 + x^2 - x + 1) / ((x-1)^4*(x+1)*(x^2+1)*(x^4+1)). - Colin Barker, Jan 20 2015

PROG

(PARI) concat([0, 0, 0], Vec(x^4*(x^2-x+1)*(x^4+x^2-x+1) / ((x-1)^4*(x+1)*(x^2+1)*(x^4+1)) + O(x^100))) \\ Colin Barker, Jan 20 2015

CROSSREFS

Cf. A007997, A008646, A032192, A053643, A053731, A053733.

Sequence in context: A166709 A310040 A215369 * A268345 A267047 A032801

Adjacent sequences:  A053615 A053616 A053617 * A053619 A053620 A053621

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Mar 25 2000

STATUS

approved

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Last modified March 26 20:47 EDT 2019. Contains 321535 sequences. (Running on oeis4.)