Logo

Greetings from The On-Line Encyclopedia of Integer Sequences!

Hints

Search: id:A113039
Displaying 1-1 of 1 results found. page 1
     Format: long | short | internal | text      Sort: relevance | references | number      Highlight: on | off
A113039 Number of ways the set {1,2,...,n} can be split into three subsets of which the three sums are consecutive. +0
1
0, 0, 1, 0, 3, 5, 0, 23, 52, 0, 254, 593, 0, 3611, 8859, 0, 55554, 142169, 0, 946871, 2466282, 0, 17095813, 45359632, 0 (list; graph; listen)
OFFSET

1,5

FORMULA

a(n) is the coefficient of x^3y in product(x^(-2k)+x^k(y^k+y^(-k)), k=1..n) for n>2.

EXAMPLE

For n=5 we have splittings 4/23/15, 4/5/123, 13/5/24, so a(5)=3.

MAPLE

A113039:=proc(n) local i, j, p, t; t:= 0, 0; for j from 3 to n do p:=1; for i to j do p:=p*(x^(-2*i)+x^(i)*(y^i+y^(-i))); od; t:=t, coeff(coeff(p, x, 3), y, 1); od; t; end;

CROSSREFS

Cf. A112972.

Adjacent sequences: A113036 A113037 A113038 this_sequence A113040 A113041 A113042

Sequence in context: A099895 A124222 A111823 this_sequence A093016 A031018 A011353

KEYWORD

nonn

AUTHOR

Floor van Lamoen (fvlamoen(AT)hotmail.com), Oct 12 2005

page 1

Search completed in 0.002 seconds

Lookup | Welcome | Find friends | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
More pages | Superseeker | Maintained by N. J. A. Sloane (njas@research.att.com)

Last modified October 11 13:47 EDT 2008. Contains 144830 sequences.


AT&T Labs Research