|
| |
|
|
A098477
|
|
Expansion of 1/sqrt(1-2x-7x^2+8x^3).
|
|
1
| |
|
|
1, 1, 5, 9, 37, 89, 325, 905, 3109, 9337, 31173, 97449, 321445, 1027225, 3374405, 10920649, 35855909, 116937145, 384340421, 1259728873, 4147000229, 13639616473, 44978045765, 148314302473, 489879442469, 1618600915705
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
COMMENTS
| 1/sqrt(1-2x-(4r-1)x^2+4r^3) expands to give sum{k=0..floor(n/2), binomial(2k,k)binomial(n-k,n-2k)r^k}
|
|
|
FORMULA
| a(n)=sum{k=0..floor(n/2), binomial(2k, k)binomial(n-k, n-2k)2^k}
G.f.: 1/(1-x-4x^2/(1-0x-2x^2/(1-x-2x^2/(1-0x-2x^2/(1-x-2x^2/.... (continued fraction). [From Paul Barry (pbarry(AT)wit.ie), Dec 07 2008]
|
|
|
CROSSREFS
| Cf. A026569, A098478.
Sequence in context: A083832 A070969 A200376 * A176967 A110421 A176751
Adjacent sequences: A098474 A098475 A098476 * A098478 A098479 A098480
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Sep 10 2004
|
| |
|
|
