

A151522


Number of 1sided polyrhombs with n cells.


5



1, 2, 4, 13, 35, 120, 392, 1405, 4998, 18378, 67792, 253509, 952534, 3604624, 13699554, 52304807, 200406370, 770442286, 2970401696, 11482513428, 44491881033, 172766765654, 672186650116, 2619996250930, 10228902882021, 39996345469572, 156612023354364, 614044364443761
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OFFSET

1,2


COMMENTS

Also counts 1sided polyrects.


LINKS

Table of n, a(n) for n=1..28.
Ed Pegg, Jr., Illustrations of polyforms
Eric Weisstein's World of Mathematics, Polyrhomb
Eric Weisstein's World of Mathematics, Polyrect
Wikipedia, Polyomino


FORMULA

a(n) = 4*A006749(n) + 2*A006746(n) + 2*A006748(n) + 4*A006747(n) + 2*A056877(n) + 2*A056878(n) + 2*A144553(n) + A142886(n).  Andrew Howroyd, Dec 04 2018


MATHEMATICA

A[n_] := With[{n6 = StringPadLeft[ToString[n], 6, "0"]}, Cases[ Import[ "https://oeis.org/A" <> n6 <> "/b" <> n6 <> ".txt", "Table"], {_, _}][[All, 2]]];
A006749 = A@6749; A006746 = A@6746; A006748 = A@6748; A006747 = A@6747; A056877 = A@56877; A056878 = A@56878; A144553 = A@144553; A142886 = A@142886;
a[n_] := 4*A006749[[n]] + 2*A006746[[n]] + 2*A006748[[n]] + 4*A006747[[n]] + 2*A056877[[n]] + 2*A056878[[n]] + 2*A144553[[n]] + A142886[[n + 1]];
a /@ Range[28] (* JeanFrançois Alcover, Jan 03 2020 *)


CROSSREFS

Polyominoes by group of symmetries relating shapes considered the same: A000105 (all symmetries), A001168 (translations only), A000988 (rotations and translations), A056780 (horizontal and vertical reflections, rotations of order 2 and translations), A056783 (reflections in either diagonal, rotations of order 2 and translations), A151522 (rotations of order 2 and translations), A151525 (reflections in a horizontal line and translations), A182645 (reflections in a NESW diagonal line and translations)
Sequence in context: A189590 A189597 A148235 * A148236 A148237 A148238
Adjacent sequences: A151519 A151520 A151521 * A151523 A151524 A151525


KEYWORD

nonn,hard


AUTHOR

Ed Pegg Jr, May 13 2009


EXTENSIONS

Edited and a(13)a(18) by Joseph Myers, Nov 24 2010
a(19)a(28) from Andrew Howroyd, Dec 04 2018


STATUS

approved



