login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A291037 a(n) = (1/2)*A291036(n). 2
1, 3, 8, 23, 66, 188, 537, 1533, 4376, 12493, 35664, 101812, 290649, 829731, 2368680, 6762003, 19303866, 55107824, 157319377, 449108397, 1282094784, 3660067465, 10448598672, 29828197224, 85152217777, 243088784019, 693959105912, 1981083753503, 5655510252642 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
G.f.: -((-1 - x + x^3)/(1 - 2 x - 2 x^2 - 2 x^3 + 2 x^4 + x^6)).
a(n) = 2*a(n-1) + 2*a(n-2) + 2*a(n-3) - 2*a(n-4) - a(n-6) for n >= 7.
MATHEMATICA
z = 60; s = x/(x - x^3); p = 1 - 2 s - 2 s^2;
Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A079978 *)
u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A291036 *)
u/2 (* A291037 *)
LinearRecurrence[{2, 2, 2, -2, 0, -1}, {1, 3, 8, 23, 66, 188}, 30] (* Harvey P. Dale, Sep 24 2017 *)
CROSSREFS
Sequence in context: A176880 A078054 A018043 * A147704 A116410 A199841
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Sep 14 2017
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)