|
|
A140992
|
|
a(0) = 0, a(1) = 1; for n > 1, a(n) = a(n-2) + a(n-1) + A000071(n+1).
|
|
1
|
|
|
0, 1, 2, 5, 11, 23, 46, 89, 168, 311, 567, 1021, 1820, 3217, 5646, 9849, 17091, 29523, 50794, 87081, 148820, 253611, 431087, 731065, 1237176, 2089633, 3523226, 5930669, 9968123, 16730831, 28045222, 46954361, 78524160, 131181407
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 3*a(n-1) - a(n-2) - 3*a(n-3) + a(n-4) + a(n-5).
G.f.: -x*(1 - x + x^3) / ( (x - 1)*(x^2 + x - 1)^2 ). (End)
|
|
EXAMPLE
|
If n = 4, then a(4) = a(4-2) + a(4-1) + A000071(4+1) = a(2) + a(3) + A000071(5) = 2 + 5 + 4 = 11.
|
|
MATHEMATICA
|
LinearRecurrence[{3, -1, -3, 1, 1}, {0, 1, 2, 5, 11}, 40] (* Harvey P. Dale, Jun 12 2014 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Corrected (5980669 replaced by 5930669) by R. J. Mathar, Apr 27 2010
|
|
STATUS
|
approved
|
|
|
|