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

Author

Omar E. Pol, Sep 16 2012

Keywords

• nonn

Links

• Jean-François Alcover, Table of n, a(n) for n = 1..28
• Eric Weisstein's World of Mathematics, Polyomino
• Wikipedia, Polyomino

Crossrefs

Bisection of A001168.

Cf. A210987, A210988, A210996,

Programs

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 *)

Formula

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