|
| |
|
|
A108486
|
|
Sum binomial(2n-2k,2k)3^k*2^(n-k), k=0..floor(n/2).
|
|
1
| |
|
|
1, 2, 10, 80, 412, 2456, 14680, 85376, 503056, 2959136, 17381536, 102199040, 600757696, 3531251072, 20758107520, 122021457920, 717273440512, 4216334967296, 24784750512640, 145691471876096, 856414086962176
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
COMMENTS
| In general, sum{k=0..floor(n/2), C(2n-2k,2k)a^k*b^(n-k)} has expansion (1-bx-abx^2)/(1-2bx-(2ab-b^2)x^2-2ab^2*x^3+(ab)^2*x^4).
|
|
|
FORMULA
| G.f.: (1-2x-6x^2)/(1-4x-8x^2-24x^3+36x^4); a(n)=4a(n-1)+8a(n-2)+24a(n-3)-36a(n-4).
|
|
|
CROSSREFS
| Sequence in context: A098636 A081363 A100248 * A152168 A003578 A152600
Adjacent sequences: A108483 A108484 A108485 * A108487 A108488 A108489
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jun 04 2005
|
| |
|
|
