|
Search: id:A006482
|
|
|
| A006482 |
|
Euler characteristics of polytopes.
(Formerly M1357)
|
|
+0
1
|
|
| 1, 1, 0, 2, 5, 9, 14, 20, 69, 125, 209, 329, 923, 1715, 3002, 5004, 12869, 24309, 43757, 75581, 184755, 352715, 646645, 1144065, 2704155, 5200299, 9657699, 17383859, 40116599
(list; graph; listen)
|
|
|
OFFSET
|
1,4
|
|
|
REFERENCES
|
H. Hadwiger and P. Mani, On polyhedra with extremal Euler characteristic, J. Combin. Theory, A 17 (1974), 345-349.
|
|
FORMULA
|
Numbers suggest that for n>3, a(n) = C(n, [n/2])-1 if (n mod 4)=0 or 1, and C(n, [n/2]-1)-1 otherwise. - R. Stephan, Jun 07 2005
|
|
PROGRAM
|
(PARI) a(n)=if(n<3, (n==0||n==1), if(n<4, 2, -1+if(n%4==0||n%4==1, binomial(n, n\2), binomial(n, n\2-1)))) /* (from R. Stephan) */
|
|
CROSSREFS
|
Sequence in context: A112873 A048093 A024669 this_sequence A139423 A026053 A011905
Adjacent sequences: A006479 A006480 A006481 this_sequence A006483 A006484 A006485
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
njas
|
|
|
Search completed in 0.002 seconds
|
