|
Search: id:A151998
|
|
|
| A151998 |
|
Directed genus of the binary de Bruijn graph D_n. |
|
+0
1
|
|
| 0, 0, 0, 1, 2, 7, 15, 35, 75, 163, 337, 709, 1458, 3001, 6135, 12529, 25468, 51739, 104829, 212205, 428916, 866215, 1747527, 3523213, 7097895, 14291683, 28760643, 57852469, 116321445, 233798623, 469761015, 943591237, 1894836585, 3804113881, 7635493643
(list; graph; listen)
|
|
|
OFFSET
|
0,5
|
|
|
REFERENCES
|
A. W. Hales and N. Hartsfield, The directed genus of the de Brijn grpah, Discrete Math., 309 (2009), 5259-5263.
|
|
FORMULA
|
See Maple code.
|
|
MAPLE
|
with(numtheory);
f:=proc(n) local t1, t2, t3, i;
t1:=divisors(n+2); t2:=convert(t1, list);
t3:=add( phi(t2[i])*2^((n+2)/t2[i]), i =1..nops(t2));
2^(n-1) + 1 - t3/(2*(n+2));
end;
|
|
CROSSREFS
|
Sequence in context: A147672 A095091 A131412 this_sequence A052130 A065506 A121165
Adjacent sequences: A151995 A151996 A151997 this_sequence A151999 A152000 A152001
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com), Sep 15 2009
|
|
|
Search completed in 0.002 seconds
|
