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A065128 Number of invertible n X n matrices mod 4 (i.e., over the ring Z_4). 4
1, 2, 96, 86016, 1321205760, 335522845163520, 1385295986380096143360, 92239345887620476544860815360, 98654363640526679389774053813465907200, 1691558770638735027870457216848672340872423014400, 464518059995994038184379206447729320401459864818351813427200 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
Geoffrey Critzer, Combinatorics of Vector Spaces over Finite Fields, Master's thesis, Emporia State University, 2018.
J. Overbey, W. Traves and J. Wojdylo, On the Keyspace of the Hill Cipher
FORMULA
a(n) = 4^(n^2) * Product_{k=1..n} (1 - 1/2^k).
a(n) = 2^(n^2) * A002884(n). - Geoffrey Critzer, Feb 04 2018
MATHEMATICA
a(0) = 1. a[n_] := 4^(n^2)*Product[1 - 1/2^k, {k, 1, n} ]; Table[ a[n], {n, 0, 10} ]
PROG
(PARI) for(n=1, 11, print(4^(n^2)*prod(k=1, n, (1-1/2^k))))
CROSSREFS
Column k=4 of A316622.
Cf. A053291.
Sequence in context: A119696 A264542 A064069 * A122222 A036980 A337653
KEYWORD
nonn
AUTHOR
Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Nov 14 2001
EXTENSIONS
More terms from Robert G. Wilson v and Jason Earls, Nov 16 2001
STATUS
approved

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Last modified March 28 04:13 EDT 2024. Contains 371235 sequences. (Running on oeis4.)