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 A095421 Triangle read by rows: T(n,m) = number of m-block proper covers (without empty blocks and without multiple blocks) of a labeled n-set (n>=2, 2<=m<=2^n-2). 2

%I

%S 1,6,17,15,6,1,25,230,861,1918,2975,3428,3003,2002,1001,364,91,14,1,

%T 90,2125,20930,127701,568820,2003635,5820750,14282125,30030000,

%U 54620475,86490950,119759325,145422600,155117515,145422675,119759850,86493225

%N Triangle read by rows: T(n,m) = number of m-block proper covers (without empty blocks and without multiple blocks) of a labeled n-set (n>=2, 2<=m<=2^n-2).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ProperCover.html">Proper Cover.</a>

%F T(n, m) = Sum((-1)^(n-i)*binomial(n, i)*binomial(2^i-1, m), i=1..n) - binomial(2^n-2, m-1).

%e 1;

%e 6,17,15,6,1;

%e 25,230,861,1918,2975,3428,3003,2002,1001,364,91,14,1;

%e ...

%Y Cf. A007537(row sums), A055154, A055127, A055152, A095422, A095423.

%K easy,nonn,tabf,changed

%O 2,2

%A Goran Kilibarda, _Vladeta Jovovic_, Jun 04 2004

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