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A065068 Number of fixed polyominoes with n cells of which no four are equally spaced on a straight line. 2
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 (list; graph; refs; listen; history; text; internal format)
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

CROSSREFS

Cf. A001168.

Sequence in context: A000996 A309757 A020963 * A109961 A288029 A268655

Adjacent sequences:  A065065 A065066 A065067 * A065069 A065070 A065071

KEYWORD

nonn

AUTHOR

Jan Kristian Haugland, Nov 07 2001

EXTENSIONS

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

STATUS

approved

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Last modified April 12 18:58 EDT 2021. Contains 342932 sequences. (Running on oeis4.)