|
| |
|
|
A091593
|
|
Reversion of Jacobsthal numbers A001045.
|
|
4
| |
|
|
1, -1, -1, 5, -3, -21, 51, 41, -391, 407, 1927, -6227, -2507, 49347, -71109, -236079, 966129, 9519, -7408497, 13685205, 32079981, -167077221, 60639939, 1209248505, -2761755543, -4457338681, 30629783831, -22124857219, -206064020315, 572040039283, 590258340811
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,4
|
|
|
COMMENTS
| Hankel transform is (-2)^C(n+1,2). [From Paul Barry (pbarry(AT)wit.ie), Apr 28 2009]
|
|
|
LINKS
| Index entries for reversions of series
|
|
|
FORMULA
| G.f.: (-(1+x)+sqrt(1+2x+9x^2))/(4x)
a(n)=sum{k=0..floor(n/2), binomial(n, 2k)*C(k)*(-1)^(n-k)2^k}, where C(n) is A000108. - Paul Barry (pbarry(AT)wit.ie), May 16 2005
G.f.: 1/(1+x+2x^2/(1+x+2x^2/(1+x+2x^2/(1+x+2x^2/(1+ ... (continued fraction). [From Paul Barry (pbarry(AT)wit.ie), Apr 28 2009]
a(n)=sum(i=0..n, 2^(i)*(-1)^(n-i)*binomial(n+1,i)^2*(n-i+1)/(i+1))/(n+1). [From Vladimir Kruchinin, Oct 12 2011]
|
|
|
PROG
| (Maxima)
a(n):=sum(2^(i)*(-1)^(n-i)*binomial(n+1, i)^2*(n-i+1)/(i+1), i, 0, n)/(n+1); [From Vladimir Kruchinin, Oct 12 2011]
|
|
|
CROSSREFS
| Sequence in context: A199636 A199638 A154825 * A139699 A069607 A128366
Adjacent sequences: A091590 A091591 A091592 * A091594 A091595 A091596
|
|
|
KEYWORD
| easy,sign
|
|
|
AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Jan 23 2004
|
| |
|
|
