%I A007537 M5287
%S A007537 0,1,45,15913,1073579193,4611686005542975085,
%T A007537 85070591730234615801280047645054636261,
%U A007537 28948022309329048855892746252171976961956366698726387156269151989162886489297
%N A007537 Number of proper covers of an n-set.
%D A007537 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A007537 A. J. Macula, Covers of a finite set, Math. Mag., 67 (1994), 141-144.
%H A007537 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               ProperCover.html">Link to a section of The World of Mathematics.</
               a>
%p A007537 A007537 := proc(n) 1/2*sum((-1)^k*binomial(n,k)*2^(2^(n-k)),k=0..n)-2^(2^n)/
               4 end;
%Y A007537 Cf. A003465.
%Y A007537 Sequence in context: A134229 A163035 A101994 this_sequence A125113 A003739 
               A145319
%Y A007537 Adjacent sequences: A007534 A007535 A007536 this_sequence A007538 A007539 
               A007540
%K A007537 nonn,easy,nice
%O A007537 1,3
%A A007537 N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
%E A007537 One more term from Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 01 
               2005