A211877 Number of involutions in GL(n,4).

1, 21, 673, 102273, 47663617, 110981851137, 815432848809985, 30052835284679819265, 3519512226295269640765441, 2069751512310185039905834926081, 3874510079394593253089862950754189313, 36431456010689490638771956423547489198538753

Offset: 1

Author

Alexander Gruber, Feb 12 2013

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..50

Programs

Maple

A211877 := proc(n)
    add( 4^(k*(n-k))*A022168(n,k),k=1..n) ;
end proc: # R. J. Mathar, Apr 26 2013

Mathematica

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