|
Search: id:A139087
|
|
|
| A139087 |
|
G.f. satisfies: 3*A(x) = 5*x + x^2 - 2*Series_Reversion( A(x) ). |
|
+0
2
|
|
| 1, 1, -4, 50, -892, 19740, -508152, 14692470, -467083420, 16099792940, -595887304312, 23516941477900, -984430022672264, 43531470067595800, -2026833072292353360, 99096914857692255930, -5076210296937439870524
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
FORMULA
|
a(n) = (2/3)*(-1)^n*A139088(n) for n>2 with a(1)=a(2)=1.
|
|
EXAMPLE
|
G.f.: A(x) = x + x^2 - 4*x^3 + 50*x^4 - 892*x^5 + 19740*x^6 -+...
Series_Reversion(A(x)) = x - x^2 + 6*x^3 - 75*x^4 + 1338*x^5 -+...
which equals -G(-x) where G(x) = g.f. of A139088.
|
|
PROGRAM
|
(PARI) {a(n)=local(A=x+x^2); if(n<1, 0, for(i=3, n+1, A=A-2*polcoeff(serreverse(A+x*O(x^i)), i)*x^i); polcoeff(A, n))}
|
|
CROSSREFS
|
Cf. A139088.
Adjacent sequences: A139084 A139085 A139086 this_sequence A139088 A139089 A139090
Sequence in context: A028455 A114480 A123356 this_sequence A026865 A016078 A122464
|
|
KEYWORD
|
sign
|
|
AUTHOR
|
Paul D. Hanna (pauldhanna(AT)juno.com), Apr 08 2008
|
|
|
Search completed in 0.002 seconds
|
