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 A083402 Let A_n be the upper triangular matrix in the group GL(n,2) that has zero entries below the main diagonal and 1 elsewhere; a(n) is the size of the conjugacy class of this matrix in GL(n,2). 3
 1, 3, 42, 2520, 624960, 629959680, 2560156139520, 41781748196966400, 2732860586067178291200, 715703393163961188325785600, 750102961052993818881476159078400, 3145391744524297920839316348340273152000, 52764474940208177704130232748554603290689536000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Eric M. Schmidt, Table of n, a(n) for n = 1..30 FORMULA a(n) = A002884(n) / 2^(n-1). EXAMPLE For example for n=4 the matrix is / 1,1,1,1 / 0,1,1,1 / 0,0,1,1 / 0,0,0,1 /. MAPLE a:= n-> 2^((n-1)*(n-2)/2) *mul(2^k-1, k=1..n): seq(a(n), n=1..15);  # Alois P. Heinz, May 14 2013 MATHEMATICA a[n_] := 2^((n-1)*(n-2)/2)*Product[2^k-1, {k, 1, n}]; Table[a[n], {n, 1, 15}] (* Jean-François Alcover, Feb 17 2014, after Alois P. Heinz *) CROSSREFS Cf. A002884, A070731, A082877, A062383. Sequence in context: A331705 A156108 A210929 * A145984 A213956 A157552 Adjacent sequences:  A083399 A083400 A083401 * A083403 A083404 A083405 KEYWORD nonn AUTHOR Yuval Dekel (dekelyuval(AT)hotmail.com), Jun 12 2003 EXTENSIONS More terms from Eric M. Schmidt, May 14 2013 STATUS approved

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Last modified September 25 09:40 EDT 2021. Contains 347654 sequences. (Running on oeis4.)