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Number of involutions in GL(n,4).
1

%I #16 Aug 23 2013 13:57:33

%S 1,21,673,102273,47663617,110981851137,815432848809985,

%T 30052835284679819265,3519512226295269640765441,

%U 2069751512310185039905834926081,3874510079394593253089862950754189313,36431456010689490638771956423547489198538753

%N Number of involutions in GL(n,4).

%H Alois P. Heinz, <a href="/A211877/b211877.txt">Table of n, a(n) for n = 1..50</a>

%p A211877 := proc(n)

%p add( 4^(k*(n-k))*A022168(n,k),k=1..n) ;

%p end proc: # _R. J. Mathar_, Apr 26 2013

%t Sum[q^(k (n - k)) QBinomial[n, k, q], {k, 1, n}]

%K nonn

%O 1,2

%A _Alexander Gruber_, Feb 12 2013