|
| |
|
|
A122802
|
|
Number of labeled bipartite graphs on n vertices with no isolated vertices.
|
|
2
|
|
|
|
1, 0, 1, 6, 29, 510, 5032, 161406, 3294405, 194342910, 7934652356, 881008805886, 71275547085536, 15178191426486270, 2434250064518832302, 1008694542117649154046, 321680912414994434144165, 262063364967549826752315390, 166681427053102507699172431372
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,4
|
|
|
LINKS
|
Andrew Howroyd, Table of n, a(n) for n = 0..50
|
|
|
FORMULA
|
a(2n+1) = A052332(2n+1); a(2n) = A052332(2n) - A122801(n) for n > 0.
|
|
|
PROG
|
(PARI) a(n)={sum(k=0, n, binomial(n, k)*(2^k-2)^(n-k)) - if(n%2==0&&n>0, binomial(n-1, n/2)*sum(k=0, n/2, binomial(n/2, k)*(-1)^k*(2^(n/2-k)-1)^(n/2)))} \\ Andrew Howroyd, Nov 07 2019
|
|
|
CROSSREFS
|
Cf. A122801, A052332, A001831, A002031, A047863.
Sequence in context: A266205 A344434 A321141 * A144746 A051685 A326858
Adjacent sequences: A122799 A122800 A122801 * A122803 A122804 A122805
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Max Alekseyev, Sep 11 2006
|
|
|
EXTENSIONS
|
Terms a(17) and beyond from Andrew Howroyd, Nov 07 2019
|
|
|
STATUS
|
approved
|
| |
|
|
