|
| |
|
|
A069996
|
|
Number of spanning trees on the bipartite graph K_{3,n}.
|
|
4
| |
|
|
1, 12, 81, 432, 2025, 8748, 35721, 139968, 531441, 1968300, 7144929, 25509168, 89813529, 312487308, 1076168025, 3673320192, 12440502369, 41841412812, 139858796529, 464904586800, 1537671920841, 5062810950252, 16600580533161
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| With a leading zero, this is the second binomial transform of the octagonal numbers A000567 and the binomial transform of A084857. - Paul Barry (pbarry(AT)wit.ie), Jun 09 2003
|
|
|
FORMULA
| a(n) = n^2 * 3^(n-1)
E.g.f.: exp(3x)(x+3x^2) - Paul Barry (pbarry(AT)wit.ie), Jul 23 2003
|
|
|
MATHEMATICA
| a[n_] := n^2*3^(n - 1); Table[ a[n], {n, 1, 24}]
|
|
|
CROSSREFS
| Sequence in context: A012195 A147650 A007010 * A183504 A194493 A163020
Adjacent sequences: A069993 A069994 A069995 * A069997 A069998 A069999
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Eric Weinhandl (eweinhandl(AT)msn.com), May 01 2002
|
|
|
EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), May 04 2002
|
| |
|
|
