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A156433 Number of nXn 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; internal format)
OFFSET

3,2

CROSSREFS

Sequence in context: A073111 A013369 A013416 * A169771 A008551 A183896

Adjacent sequences:  A156430 A156431 A156432 * A156434 A156435 A156436

KEYWORD

nonn

AUTHOR

R. H. Hardin (rhhardin(AT)att.net) Feb 09 2009

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Last modified February 15 08:40 EST 2012. Contains 205731 sequences.