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A338213 a(n) is the number of free polyominoes with sprawl n. 3
1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 3, 2, 4, 6, 13, 15, 30, 50, 93, 158, 287, 513, 950, 1735, 3212, 5945, 11099, 20720, 38910, 73002, 137821, 259757 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,13

COMMENTS

The sprawl of a polyomino is the number of cells in a polyomino plus the number of cells adjacent to it.

LINKS

Table of n, a(n) for n=0..33.

Sean A. Irvine, Java program (github)

FORMULA

Antidiagonal sums of A338211.

CROSSREFS

Cf. A000105, A338211, A338212.

Sequence in context: A039915 A085346 A121861 * A317736 A060006 A123097

Adjacent sequences:  A338210 A338211 A338212 * A338214 A338215 A338216

KEYWORD

nonn,more

AUTHOR

Sean A. Irvine and Allan C. Wechsler, Oct 17 2020

STATUS

approved

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Last modified March 5 16:55 EST 2021. Contains 341827 sequences. (Running on oeis4.)