A107384 - OEIS

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A107384

a(n)= a(n-1) +3*a(n-2) -3*a(n-4).

0, 1, 1, 2, 5, 8, 20, 38, 83, 173, 362, 767, 1604, 3386, 7112, 14969, 31493, 66242, 139385, 293204, 616880, 1297766, 2730251, 5743937, 12084050, 25422563, 53483960, 112519838, 236719568, 498011393, 1047718217, 2204192882

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..31.

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

FORMULA

Limit a(n)/a(n-1)=2.1038034027..

G.f.: x*(-1+2*x^2)/((1-x) * (3*x^3+3*x^2-1)). [Sep 28 2009]

MATHEMATICA

m = 3 a[0] = 0; a[1] = 1; a[2] = 1; a[3] = 2; a[n_] := a[n] = a[n - 1] + m*a[n - 2] - m*a[n - 4] digits = 50 aa = Table[a[n], {n, 0, digits}]

LinearRecurrence[{1, 3, 0, -3}, {0, 1, 1, 2}, 40] (* Harvey P. Dale, Aug 24 2017 *)