|
| |
|
|
A063866
|
|
Number of solutions to +- 1 +- 2 +- 3 +- ... +- n = 1.
|
|
9
|
|
|
|
0, 1, 1, 0, 0, 3, 5, 0, 0, 23, 40, 0, 0, 221, 397, 0, 0, 2410, 4441, 0, 0, 28460, 53222, 0, 0, 353743, 668273, 0, 0, 4559828, 8679280, 0, 0, 60400688, 115633260, 0, 0, 817175698, 1571588177, 0, 0, 11243980807, 21704569869, 0, 0, 156860869714
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,6
|
|
|
REFERENCES
|
Suggested by J. H. Conway (conway(AT)math.princeton.edu), Aug 27, 2001.
|
|
|
LINKS
|
T. D. Noe, Table of n, a(n) for n=0..100
|
|
|
MATHEMATICA
|
f[n_, s_] := f[n, s]=Which[n==0, If[s==0, 1, 0], Abs[s]>(n*(n+1))/2, 0, True, f[ n-1, s-n]+f[n-1, s+n]]; a[n_] := f[n, 1]
|
|
|
CROSSREFS
|
Cf. A025591, A063865, A063867.
Sequence in context: A059107 A025115 A113037 * A059106 A087676 A058813
Adjacent sequences: A063863 A063864 A063865 * A063867 A063868 A063869
|
|
|
KEYWORD
|
nonn,easy,nice
|
|
|
AUTHOR
|
N. J. A. Sloane, Aug 27 2001
|
|
|
EXTENSIONS
|
More terms from Dean Hickerson and Vladeta Jovovic, Aug 28, 2001
|
|
|
STATUS
|
approved
|
| |
|
|
