|
|
A007715
|
|
Number of 5-leaf rooted trees with n levels.
|
|
2
|
|
|
1, 7, 27, 75, 170, 336, 602, 1002, 1575, 2365, 3421, 4797, 6552, 8750, 11460, 14756, 18717, 23427, 28975, 35455, 42966, 51612, 61502, 72750, 85475, 99801, 115857, 133777, 153700, 175770, 200136, 226952, 256377, 288575, 323715, 361971, 403522, 448552, 497250
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
B. A. Huberman and T. Hogg, Complexity and adaptation, Evolution, games and learning (Los Alamos, N.M., 1985). Phys. D 22 (1986), no. 1-3, 376-384.
|
|
FORMULA
|
Expansion of x*(1+2x+2x^2)/(1-x)^5.
a(n) = n*(n+1)*(5*n^2+n+6)/24. - T. D. Noe, Feb 09 2007
a(1)=1, a(2)=7, a(3)=27, a(4)=75, a(5)=170, a(n)=5*a(n-1)- 10*a(n-2)+ 10*a(n-3)-5*a(n-4)+a(n-5). - Harvey P. Dale, Jul 20 2011
|
|
EXAMPLE
|
a(7) = 7*28 - (7*0+4*1+1*3-2*6-5*10-8*15-11*21) = 602. - Bruno Berselli, Jun 22 2013
|
|
MATHEMATICA
|
Table[n(n+1)(5n^2+n+6)/24, {n, 40}] (* or *) LinearRecurrence[ {5, -10, 10, -5, 1}, {1, 7, 27, 75, 170}, 40] (* Harvey P. Dale, Jul 20 2011 *)
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|