|
Search: id:A007043
|
|
|
| A007043 |
|
Number of noncommutative SL(2,C)-invariants of degree n in 5 variables.
(Formerly M3870)
|
|
+0
1
|
|
| 1, 0, 1, 1, 5, 16, 65, 260, 1085, 4600, 19845, 86725, 383251, 1709566, 7687615, 34812519, 158614405, 726612216, 3344696501, 15462729645, 71763732545
(list; graph; listen)
|
|
|
OFFSET
|
0,5
|
|
|
REFERENCES
|
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Almkvist, Gert; Dicks, Warren; Formanek, Edward; Hilbert series of fixed free algebras and noncommutative classical invariant theory. J. Algebra 93 (1985), no. 1, 189-214.
|
|
FORMULA
|
a(n)=sum{k=0..n, sum{j=0..k, C(n,k)C(k,j)(-3)^(k-j)A000108(j)}}; a(n)=(1/(2*pi))*int((1-3x+x^2)^n*sqrt(x(4-x))/x,x,0,4); - Paul Barry (pbarry(AT)wit.ie), Oct 18 2007
|
|
CROSSREFS
|
Sequence in context: A034532 A092497 A026525 this_sequence A128242 A166932 A027105
Adjacent sequences: A007040 A007041 A007042 this_sequence A007044 A007045 A007046
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)
|
|
|
Search completed in 0.002 seconds
|
