|
Search: id:A007537
|
|
|
| A007537 |
|
Number of proper covers of an n-set.
(Formerly M5287)
|
|
+0
6
|
|
| 0, 1, 45, 15913, 1073579193, 4611686005542975085, 85070591730234615801280047645054636261, 28948022309329048855892746252171976961956366698726387156269151989162886489297
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
REFERENCES
|
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
A. J. Macula, Covers of a finite set, Math. Mag., 67 (1994), 141-144.
|
|
LINKS
|
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
|
|
MAPLE
|
A007537 := proc(n) 1/2*sum((-1)^k*binomial(n, k)*2^(2^(n-k)), k=0..n)-2^(2^n)/4 end;
|
|
CROSSREFS
|
Cf. A003465.
Adjacent sequences: A007534 A007535 A007536 this_sequence A007538 A007539 A007540
Sequence in context: A134229 A163035 A101994 this_sequence A125113 A003739 A145319
|
|
KEYWORD
|
nonn,easy,nice
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
|
|
EXTENSIONS
|
One more term from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 01 2005
|
|
|
Search completed in 0.002 seconds
|
