A209984 Number of 2 X 2 matrices having all elements in {-n,...n} and determinant 2.

0, 4, 92, 156, 284, 412, 604, 796, 1052, 1244, 1628, 1948, 2204, 2588, 3164, 3420, 3932, 4444, 5020, 5596, 6108, 6492, 7452, 8156, 8668, 9308, 10460, 11036, 11804, 12700, 13468, 14428, 15452, 16092, 17628, 18396, 19164, 20316, 22044

Offset

0,2

Comments

See A210000 for a guide to related sequences.

Links

Chai Wah Wu, Table of n, a(n) for n = 0..10000

Example

a(1) counts these matrices (in reduced notation):
(-1,-1,1,-1), (-1,1,-1,-1), (1,-1,1,1), (1,1,-1,1)

Mathematica

(See the Mathematica section at A209981.)

Crossrefs

Cf. A210000.

Sequence in context: A337827 A129434 A248041 * A113252 A003737 A362511

Adjacent sequences: A209981 A209982 A209983 * A209985 A209986 A209987

Keyword

nonn

Author

Clark Kimberling, Mar 17 2012

Status

approved