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A171010 Number of ways to place two non-attacking kings on all free n-ominoes. 0
0, 0, 1, 7, 46, 240, 1207, 6004, 28903, 137996 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

E.g. the triomino XXX admits 1 combination of 2 non-attacking kings.

CROSSREFS

Sequence in context: A175909 A034471 A100024 * A258630 A264201 A086092

Adjacent sequences:  A171007 A171008 A171009 * A171011 A171012 A171013

KEYWORD

nonn

AUTHOR

David Scambler, Aug 27 2010

STATUS

approved

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Last modified September 25 13:01 EDT 2020. Contains 337344 sequences. (Running on oeis4.)