|
|
A107699
|
|
Bisection (odd-indexed terms) of A107700.
|
|
2
|
|
|
1, 1, -2, 13, -145, 2328, -49784, 1358965, -46076544, 1902202515, -94104681660, 5503867176832, -376096374571125, 29714871818774044, -2689473418781240320, 276562260699626541509, -32073434441440654231749, 4167256779254698145624064, -603002974281204853457239860
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
FORMULA
|
G.f.: A(x) = (G(x) - G(-x))/2, where G(x) is the g.f. of A107700 and satisfies: G(G(x)) = x + 2*G(x)^2.
|
|
MATHEMATICA
|
a[n_] := Module[{A, B, F}, A = Series[x+x^2+x^(2*n), {x, 0, 2*n}]; If[n<1, 0, For[i=0, i <= 2*n, i++, F = x+2*A^2; B = InverseSeries[A]; A = (A+(B /. x -> F))/2]; SeriesCoefficient[A, {x, 0, 2*n-1}]]]; Table[a[n], {n, 1, 19}] (* Jean-François Alcover, Feb 04 2014, after PARI *)
|
|
PROG
|
(PARI) {a(n)=local(A, B, F); A=x+x^2+x*O(x^(2*n)); if(n<1, 0, for(i=0, 2*n, F=x+2*A^2; B=serreverse(A); A=(A+subst(B, x, F))/2); polcoeff(A, 2*n-1, x))}
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|