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A156430 Number of nXn arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 2. 0
1, 2, 10, 12, 84, 132, 954, 1728, 13290, 26820, 217500, 481320, 4086600, 9783480, 86549820, 221921280, 2037627900, 5552479800, 52745205240, 151802154000, 1487961422640, 4500041903280, 45412066438200, 143712079822080 (list; graph; refs; listen; history; internal format)
OFFSET

2,2

CROSSREFS

Sequence in context: A181427 A055697 A055705 * A095914 A189079 A045218

Adjacent sequences:  A156427 A156428 A156429 * A156431 A156432 A156433

KEYWORD

nonn

AUTHOR

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

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Last modified February 17 00:09 EST 2012. Contains 205978 sequences.