|
| |
|
|
A059678
|
|
Triangle T(n,k) giving number of fixed 2 X k polyominoes with n cells (n >= 2, 1<=k<=n-1).
|
|
0
| |
|
|
1, 0, 4, 0, 1, 8, 0, 0, 6, 12, 0, 0, 1, 18, 16, 0, 0, 0, 8, 38, 20, 0, 0, 0, 1, 32, 66, 24, 0, 0, 0, 0, 10, 88, 102, 28, 0, 0, 0, 0, 1, 50, 192, 146, 32, 0, 0, 0, 0, 0, 12, 170, 360, 198, 36, 0, 0, 0, 0, 0, 1, 72, 450, 608, 258, 40, 0, 0, 0, 0, 0, 0, 14, 292, 1002, 952, 326, 44, 0, 0, 0
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 2,3
|
|
|
REFERENCES
| R. C. Read, Contributions to the cell growth problem, Canad. J. Math., 14 (1962), 1-20.
|
|
|
FORMULA
| T(n, k) = Sum_v C(n-k+1, 2*k-n-v)*C(n-k+v, n-k).
G.f. (1+x*y)^2/(1-x*y)*1/((1-x*y)-(1+x*y)*x^2*y); - Christopher Hanusa (chanusa(AT)math.washington.edu), Sep 22 2004
|
|
|
EXAMPLE
| 1; 0,4; 0,1,8; 0,0,6,12; ...
|
|
|
MAPLE
| with(combinat): for n from 2 to 30 do for k from 1 to n-1 do printf(`%d, `, sum(binomial(n-k+1, 2*k-n-v)*binomial(n-k+v, n-k), v=0..k) ) od:od:
|
|
|
CROSSREFS
| Sequence in context: A097898 A154884 A201560 * A079642 A121408 A186761
Adjacent sequences: A059675 A059676 A059677 * A059679 A059680 A059681
|
|
|
KEYWORD
| nonn,easy,nice
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Feb 05 2001
|
|
|
EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Feb 06 2001
|
| |
|
|
