|
| |
|
|
A133106
|
|
Number of Ferrers diagrams with a single Ferrers puncture with the same orientation inscribed strictly inside with half-perimeter=n.
|
|
2
| |
|
|
1, 8, 41, 168, 602, 1968, 6021, 17512, 48950, 132496, 349258, 900368, 2277556, 5667936, 13906221, 33695208, 80746846, 191601872, 450642654, 1051472048, 2435679852, 5605044640, 12820922530, 29164511376, 66004709148, 148678206880
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 8,2
|
|
|
LINKS
| Charles R Greathouse IV, Table of n, a(n) for n = 8..3296
|
|
|
FORMULA
| a(n)=[(2*n^2-16*n+6)*a(n-1)+(4*n^2-68*n+240)*a(n-2)-(8*n^2-88*n+240)*a(n-3)]/(n^2-14*n+48) with a(6)=0, a(7)=0, a(8)=1. G.F.=(1-(1-4*x^2)^(1/2))*x^6/(2*(2*x-1)^4)
|
|
|
EXAMPLE
| The sequence starts with n=8 because the smallest such object whose cartoon is below has a perimeter of 16. (1 denotes cell outside the puncture and 2 denotes cell inside the puncture).
111
121
111
|
|
|
CROSSREFS
| Cf. A057410, A057406, A133107.
Sequence in context: A041116 A135797 A171714 * A078797 A176177 A156790
Adjacent sequences: A133103 A133104 A133105 * A133107 A133108 A133109
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Arvind Ayyer (ayyer(AT)physics.rutgers.edu), Sep 11 2007
|
| |
|
|
