A065068 - OEIS

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

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OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..53.

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

FORMULA

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