|
|
A168658
|
|
a(n) = ceiling(n^n/2).
|
|
16
|
|
|
1, 1, 2, 14, 128, 1563, 23328, 411772, 8388608, 193710245, 5000000000, 142655835306, 4458050224128, 151437553296127, 5556003412779008, 218946945190429688, 9223372036854775808, 413620130943168382089
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
Number of functions of [n] to [n] (endofunctions of degree n) up to complement to n+1.
There is only one function, and only when n=2k-1 is odd, fixed by n+1-complement, the constant function with value k.
|
|
LINKS
|
|
|
FORMULA
|
|
|
EXAMPLE
|
Ceiling(6^6/2) = 23328.
|
|
MATHEMATICA
|
Join[{1}, Table[Ceiling[n^n/2], {n, 1, 25}]] (* G. C. Greubel, Jul 28 2016 *)
|
|
PROG
|
(Sage) [ceil(n^n/2) for n in range(0, 21)]#
|
|
CROSSREFS
|
Cf. A000312 (all endofunctions of degree n)
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|