A093378 a(n) = numerator of any non-diagonal entry of the matrix A^n, where A is described in the Comments lines.

2, 12, 22, 168, 1558, 5148, 8062, 177072, 860882, 738492, 121008888, 298775878, 1232566932, 14864798542, 58374617952

Offset

1,1

Comments

A =

[ -3/5 -(2/5)i, -(2/5)i, -(2/5)i, -(2/5)i ]

[ -(2/5)i, -3/5 +(2/5)i, -(2/5)i, (2/5)i ]

[ -(2/5)i, -(2/5)i, -3/5 +(2/5)i, (2/5)i ]

[ -(2/5)i, (2/5)i, (2/5)i, -3/5 -(2/5)i ]

is the Cayley transform of the matrix iH, where H =

[1, 1, 1, 1]

[1, -1, 1, -1]

[1, 1, -1, -1]

[1, -1, -1, 1]

is a Hadamard matrix of order 4 and i is the imaginary unit.

Links

Table of n, a(n) for n=1..15.

Crossrefs

Cf. A066771.

Sequence in context: A073211 A233137 A094626 * A012664 A012545 A009514

Adjacent sequences: A093375 A093376 A093377 * A093379 A093380 A093381

Keyword

nonn,frac,more

Author

Simone Severini, Apr 28 2004

Status

approved