A211877 - OEIS

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A211877

Number of involutions in GL(n,4).

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

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OFFSET

1,2

LINKS

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

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}]

CROSSREFS

Sequence in context: A020246 A239099 A006934 * A212734 A339119 A243746

Adjacent sequences: A211874 A211875 A211876 * A211878 A211879 A211880

KEYWORD

nonn

AUTHOR

Alexander Gruber, Feb 12 2013

STATUS

approved