A210986 Number of fixed polyominoes with 2n cells.

2, 19, 216, 2725, 36446, 505861, 7204874, 104592937, 1540820542, 22964779660, 345532572678, 5239988770268, 79992676367108, 1228088671826973, 18946775782611174, 293560133910477776, 4565553929115769162, 71242712815411950635

Offset

1,1

Links

Jean-François Alcover, Table of n, a(n) for n = 1..28

Eric Weisstein's World of Mathematics, Polyomino

Wikipedia, Polyomino

Formula

a(n) = A001168(2*n).

Mathematica

A001168 = Cases[Import["https://oeis.org/A001168/b001168.txt", "Table"], {_, _}][[All, 2]];
a[n_] := A001168[[2 n]];
a /@ Range[1, Length[A001168]/2 // Floor] (* Jean-François Alcover, Sep 22 2019 *)

Crossrefs

Bisection of A001168.

Cf. A210987, A210988, A210996,

Sequence in context: A393306 A349256 A091852 * A232525 A024227 A106945

Adjacent sequences: A210983 A210984 A210985 * A210987 A210988 A210989

Keyword

nonn

Author

Omar E. Pol, Sep 16 2012

Status

approved