|
| |
|
|
A074092
|
|
Number of plane binary trees of size n+3 and contracted height n.
|
|
3
| |
|
|
1, 2, 8, 40, 144, 448, 1280, 3456, 8960, 22528, 55296, 133120, 315392, 737280, 1703936, 3899392, 8847360, 19922944, 44564480, 99090432, 219152384, 482344960, 1056964608, 2306867200, 5016387584, 10871635968, 23488102400
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
LINKS
| H. Bottomley & A. Karttunen, Notes concerning diagonals of the square arrays A073345 and A073346.
|
|
|
FORMULA
| a(0) = 1, a(1) = 2, a(n) = 2^(n-1)*(n+2)*(n-1) = (2^n)*(C(n, n-2)+C(n-1, n-2)) = 2^n * A000096(n-1).
|
|
|
MAPLE
| A074092 := n -> `if`((n < 2), n+1, 2^(n-1)*(n+2)*(n-1));
A074092v2 := n -> `if`((n < 2), n+1, (2^n)*(binomial(n, n-2)+binomial(n-1, n-2)));
|
|
|
CROSSREFS
| a(n) = A073346(n+3, n).
Sequence in context: A152458 A087971 A127919 * A003445 A181326 A186947
Adjacent sequences: A074089 A074090 A074091 * A074093 A074094 A074095
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Antti Karttunen Aug 19 2002
|
| |
|
|
