A065068 Number of fixed polyominoes with n cells of which no four are equally spaced on a straight line.

1, 2, 6, 17, 45, 114, 264, 545, 1061, 2070, 3990, 7275, 12556, 20824, 33584, 52753, 80560, 119274, 170168, 232700, 306472, 396580, 517300, 688736, 926816, 1241720, 1640968, 2130448, 2710356, 3383596, 4171788, 5120776, 6289760, 7747928, 9582196, 11908872, 14887792, 18732340, 23712492, 30141180, 38341172, 48622328, 61275752, 76578628, 94786504, 116132688, 140870564, 169379536, 202262720, 240326780, 284337040, 334532714, 389976092

Offset: 1

Author

Jan Kristian Haugland, Nov 07 2001

Keywords

• nonn

Comments

a(142) = 36 is the final nonzero term of this sequence. - Jan Kristian Haugland, Apr 28 2020

Links

• Jan Kristian Haugland, Illustration for n = 142 [Cached copy, with permission]
• J. K. Haugland, Largest polyomino with no four cells equally spaced on a straight line, arXiv:2004.12801 [math.GM] (2020).
• Wikipedia, Polyomino

Crossrefs

Cf. A001168.

Formula

a(n) = 0 for n >= 143. - Jan Kristian Haugland, Apr 28 2020

Extensions

a(32)-a(53) from Brendan Owen (brendan_owen(AT)yahoo.com), Mar 11 2002