A380575 One half of the sum of the perimeters of the free polyominoes with n cells.

2, 3, 8, 24, 71, 236, 835, 3182, 12302, 48834, 195035, 785280, 3167322, 12808531, 51834644, 209965222, 850817523, 3449091525

Offset: 1

Author

Omar E. Pol, Feb 12 2025

Keywords

• nonn
• more

Comments

A380287 is the main entry for this question.

One half of the perimeters of any holes are included here.

Links

• Index entries for sequences related to polyominoes.

Crossrefs

Cf. A000105, A342243, A380287.

Formula

a(n) = A380287(n)/2.

a(n) = Sum_{k=2..n+1} k*A342243(n,k). - Andrew Howroyd, Feb 28 2025