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A156476 Number of nXn arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to 21. 0
54, 20, 3552, 11364, 2742240, 56271108, 23882769984, 990946452040, 760348893638560 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Table of n, a(n) for n=4..12.

CROSSREFS

Sequence in context: A058283 A096510 A236178 * A137939 A033374 A116386

Adjacent sequences:  A156473 A156474 A156475 * A156477 A156478 A156479

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 09 2009

STATUS

approved

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Last modified September 17 15:30 EDT 2014. Contains 246851 sequences.