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Number of polyominoes (or square animals) with at most n cells.
9

%I #20 Apr 15 2023 15:43:21

%S 1,2,4,9,21,56,164,533,1818,6473,23546,87146,325737,1227708,4654284,

%T 17733539,67841448,260463500,1003087732,3873759682,14996820360,

%U 58188678048,226235685776,881235386179,3438462430943,13437551253018

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

%C The sequence excludes the null polyomino of size 0. - _John Mason_, Jan 10 2023

%H John Mason, <a href="/A130866/b130866.txt">Table of n, a(n) for n = 1..50</a>

%F a(n) = Sum_{k=1..n} A000105(k). - _John Mason_, Jan 10 2023

%F a(n) = A173271(n) - 1. - _John Mason_, Feb 21 2023

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

%K nonn

%O 1,2

%A _Tanya Khovanova_, Jul 23 2007

%E Offset corrected by _John Mason_, Jan 10 2023