VOOZH about

URL: https://oeis.org/A136299

⇱ A136299 - OEIS

login
A136299
a(n) = 3*a(n-1) - 4*a(n-3), with a(0)=1, a(1)=2, a(2)=4, a(3)=7.
2
1, 2, 4, 7, 13, 23, 41, 71, 121, 199, 313, 455, 569, 455, -455, -3641, -12743, -36409, -94663, -233017, -553415, -1281593, -2912711, -6524473, -14447047, -31690297, -68972999, -149130809, -320631239, -686001721, -1461481927, -3101920825, -6561755591, -13839339065
OFFSET
0,2
FORMULA
From R. J. Mathar, Apr 04 2008: (Start)
O.g.f.: (1 -x -2*x^2 -x^3)/((1+x)*(1-2*x)^2).
a(n) = (11*2^n + (-1)^n)/9 - A001787(n+1)/12 if n>0. (End)
From G. C. Greubel, Apr 12 2021: (Start)
a(n) = (2^(n-2)*(41-3*n) + (-1)^n)/9 - (1/4)*[n=0].
E.g.f.: (-9 + 4*exp(-x) + (41 - 6*x)*exp(2*x))/36. (End)
MATHEMATICA
LinearRecurrence[{3, 0, -4}, {1, 2, 4, 7}, 41] (* G. C. Greubel, Apr 12 2021 *)
PROG
(Magma) [1] cat [(2^(n-2)*(41-3*n) + (-1)^n)/9: n in [1..40]]; // G. C. Greubel, Apr 12 2021
(SageMath) [1]+[(2^(n-2)*(41-3*n) + (-1)^n)/9 for n in (1..40)] # G. C. Greubel, Apr 12 2021
CROSSREFS
Sequence in context: A239553 A319255 A392561 * A208354 A003116 A368299
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Mar 22 2008
STATUS
approved