A075111 a(n)=Sum((-1)^(i+Floor(n/2))T(2i+e),(i=0,..,Floor(n/2))), where T(n) are tribonacci numbers (A000073) and e=(1/2)(1-(-1)^n).

0, 1, 1, 1, 3, 6, 10, 18, 34, 63, 115, 211, 389, 716, 1316, 2420, 4452, 8189, 15061, 27701, 50951, 93714, 172366, 317030, 583110, 1072507, 1972647, 3628263, 6673417, 12274328, 22576008, 41523752, 76374088, 140473849, 258371689

Offset

0,5

Comments

a(n) is the convolution of T(n) with the sequence (1,0,-1,0,1,0,-1,0,....) A056594.

Links

Table of n, a(n) for n=0..34.

Index entries for linear recurrences with constant coefficients, signature (1, 0, 2, 1, 1).

Formula

a(n)=a(n-1)+2a(n-3)+a(n-4)+a(n-5), a(0)=0, a(1)=1, a(2)=1, a(3)=1, a(4)=3. G.f.: x/(1 - x - 2*x^3 - x^4 - x^5).

Mathematica

CoefficientList[Series[x/(1 - x - 2*x^3 - x^4 - x^5), {x, 0, 40}], x]

Crossrefs

Cf. A000073, A056594, A074662, A074677, A074678.

Sequence in context: A076251 A261631 A029864 * A080014 A364403 A360892

Adjacent sequences: A075108 A075109 A075110 * A075112 A075113 A075114

Keyword

easy,nonn

Author

Mario Catalani (mario.catalani(AT)unito.it), Sep 01 2002

Status

approved