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A034186 Number of symmetric n x 4 crossword puzzle grids. 2
1, 3, 21, 47, 227, 499, 2321, 5087, 23429, 51263, 235881, 515691, 2372511, 5185609, 23856215, 52139887, 239863701, 524238555, 2411688233, 5270900439, 24248031407, 52995614649 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..22.

CROSSREFS

Cf. A001333, A034184-A034187.

Sequence in context: A146712 A318549 A217000 * A318211 A219069 A027499

Adjacent sequences:  A034183 A034184 A034185 * A034187 A034188 A034189

KEYWORD

nonn

AUTHOR

Erich Friedman

STATUS

approved

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Last modified December 12 23:51 EST 2018. Contains 318081 sequences. (Running on oeis4.)