A056783 Number of diamond polyominoes with n cells.

1, 1, 3, 7, 20, 62, 204, 709, 2526, 9212, 33989, 126838, 476597, 1802618, 6850969, 26153537, 100207548, 385225375, 1485216987, 5741272625, 22246000726, 86383442996, 336093551268, 1309998354125, 5114452295933, 19998173607505, 78306014924606, 307022185565345

Offset: 1

Author

James Sellers, Aug 28 2000

Keywords

• nonn
• hard

Comments

Also the number of polybricks of size n made of Lego.

Links

• John Mason, Table of n, a(n) for n = 1..50
• Ed Pegg, Jr., Illustrations of polyforms.
• M. Keller, Counting Polyforms.
• M. Vicher, Polyforms.
• Eric Weisstein's World of Mathematics, Polyrhomb.

Crossrefs

Cf. A000105, A056780, A057973, A151522.

Formula

a(n) = 2*A006749(n) + A006746(n) + 2*A006748(n) + 2*A006747(n) + A056877(n) + 2*A056878(n) + A144553(n) + A142886(n). - Andrew Howroyd, Dec 04 2018

Extensions

More terms from Don Reble, Nov 01 2001

a(15)-a(18) from Joseph Myers, Nov 15 2010

Offset corrected and a(19)-a(28) from Andrew Howroyd, Dec 04 2018