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A156433 Number of n X n arrays of squares of integers, symmetric under 90 degree rotation, with all rows summing to 3. 0
1, 2, 0, 0, 42, 276, 0, 0, 20340, 216680, 0, 0, 30693320, 449345680, 0, 0, 105796267920, 1972495637280, 0, 0, 696951215563680, 15784392403940160, 0, 0, 7817495632183997760, 208339434598512497280, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Table of n, a(n) for n=3..30.

CROSSREFS

Sequence in context: A004076 A013369 A013416 * A169771 A326779 A293140

Adjacent sequences:  A156430 A156431 A156432 * A156434 A156435 A156436

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 09 2009

STATUS

approved

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Last modified August 9 13:54 EDT 2022. Contains 356026 sequences. (Running on oeis4.)