login
A164310
a(n) = 6*a(n-1) - 6*a(n-2) for n > 1; a(0) = 4, a(1) = 15.
1
4, 15, 66, 306, 1440, 6804, 32184, 152280, 720576, 3409776, 16135200, 76352544, 361304064, 1709709120, 8090430336, 38284327296, 181163381760, 857274326784, 4056665670144, 19196348060160, 90838094340096, 429850477679616
OFFSET
0,1
COMMENTS
Binomial transform of A077236. Inverse binomial transform of A083882 without initial 1.
FORMULA
a(n) = ((4+sqrt(3))*(3+sqrt(3))^n + (4-sqrt(3))*(3-sqrt(3))^n)/2.
G.f.: (4-9*x)/(1-6*x+6*x^2).
E.g.f.: (4*cosh(sqrt(3)*x) + sqrt(3)*sinh(sqrt(3)*x))*exp(3*x). - G. C. Greubel, Sep 13 2017
MATHEMATICA
LinearRecurrence[{6, -6}, {4, 15}, 50] (* or *) CoefficientList[Series[(4 - 9*x)/(1 - 6*x + 6*x^2), {x, 0, 50}], x] (* G. C. Greubel, Sep 13 2017 *)
PROG
(Magma) [ n le 2 select 11*n-7 else 6*Self(n-1)-6*Self(n-2): n in [1..22] ];
(PARI) x='x+O('x^50); Vec((4-9*x)/(1-6*x+6*x^2)) \\ G. C. Greubel, Sep 13 2017
CROSSREFS
Sequence in context: A369229 A097422 A102129 * A369486 A011967 A250886
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, Aug 12 2009
STATUS
approved