A359689 a(n) is the number of free polyiamonds of n cells with chessboard coloring.

2, 1, 2, 4, 8, 19, 48, 120, 320, 864, 2372, 6581, 18470, 52094, 147966, 421931, 1208214, 3470789, 10001186, 28892674, 83671476, 242823392, 706090582, 2056861981, 6001601254, 17538308071, 51323923796, 150389970179, 441211039118, 1295886198194, 3810209524640, 11214075937205, 33035791339150

Offset

1,1

Links

John Mason, Table of n, a(n) for n = 1..51

John Mason, Counting Polyiamonds

John Mason, Illustrations

Formula

See link "Counting Polyiamonds".

Crossrefs

Cf. A000577, A001933.

Sequence in context: A325665 A325843 A024739 * A024959 A029728 A135547

Adjacent sequences: A359686 A359687 A359688 * A359690 A359691 A359692

Keyword

nonn

Author

John Mason, Jan 11 2023

Extensions

More terms from John Mason, Oct 28 2023

Status

approved