A018925 Number of isotropic subspaces of a 2n-dimensional unitary space over GF(4).

5, 85, 5525, 1419925

Offset

1,1

References

D. E. Taylor, The geometry of the classical groups, Heldermann Verlag, Berlin, 1992.

Links

Table of n, a(n) for n=1..4.

C. Bachoc and G. Nebe, Classification of two genera of 32-dimensional lattices of rank 8 over the Hurwitz order, Experiment. Math. 6 (1997), 151-162.

Formula

Conjecture: a(n) = Product_{k=1..n} (4^k + 1). - Vaclav Kotesovec, Nov 21 2015

Crossrefs

Sequence in context: A012815 A113107 A317355 * A309327 A363424 A174320

Adjacent sequences: A018922 A018923 A018924 * A018926 A018927 A018928

Keyword

nonn,more

Author

N. J. A. Sloane

Status

approved