A130866 Number of polyominoes (or square animals) with at most n cells.

1, 2, 4, 9, 21, 56, 164, 533, 1818, 6473, 23546, 87146, 325737, 1227708, 4654284, 17733539, 67841448, 260463500, 1003087732, 3873759682, 14996820360, 58188678048, 226235685776, 881235386179, 3438462430943, 13437551253018

Offset: 1

Author

Tanya Khovanova, Jul 23 2007

Keywords

• nonn

Comments

The sequence excludes the null polyomino of size 0. - John Mason, Jan 10 2023

Links

• John Mason, Table of n, a(n) for n = 1..50

Crossrefs

Partial sums of A000105 starting from A000105(1). Cf. A173271.

Formula

a(n) = Sum_{k=1..n} A000105(k). - John Mason, Jan 10 2023

a(n) = A173271(n) - 1. - John Mason, Feb 21 2023

Extensions

Offset corrected by John Mason, Jan 10 2023