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A030223 Triangular polyominoes (n-iamonds) with bilateral symmetry (holes are allowed). 5
1, 1, 1, 2, 2, 5, 5, 12, 13, 30, 36, 80, 97, 213, 266, 578, 737, 1589, 2051, 4408, 5747, 12333, 16213, 34737, 45979, 98367, 131007, 279902 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..28.

CROSSREFS

Cf. A000577, A006534, A030223, A030224.

Sequence in context: A002014 A135153 A097896 * A300436 A056504 A122205

Adjacent sequences:  A030220 A030221 A030222 * A030224 A030225 A030226

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

a(19) to a(28) from Joseph Myers, Sep 24 2002

STATUS

approved

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Last modified April 17 11:26 EDT 2021. Contains 343064 sequences. (Running on oeis4.)