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A030225 Number of n-celled polyhexes (hexagonal polyominoes) with bilateral symmetry. 3
1, 1, 3, 4, 11, 17, 46, 75, 202, 341, 914, 1581, 4222, 7436, 19794, 35357, 93859, 169558, 449039, 818793 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..20.

MATHEMATICA

A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {_, _}][[All, 2]]];

A000228 = A@000228;

A006535 = A@006535;

a[n_] := 2 A000228[[n]] - A006535[[n]];

a /@ Range[20] (* Jean-Fran├žois Alcover, Feb 22 2020 *)

CROSSREFS

A030225 = 2*A000228 - A006535.

Sequence in context: A026753 A027222 A026380 * A339157 A060285 A025079

Adjacent sequences:  A030222 A030223 A030224 * A030226 A030227 A030228

KEYWORD

nonn,more

AUTHOR

David W. Wilson

EXTENSIONS

More terms from Joseph Myers, Sep 21 2002

STATUS

approved

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Last modified May 7 12:38 EDT 2021. Contains 343650 sequences. (Running on oeis4.)