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A156428 Number of 20 X 20 arrays of squares of integers, symmetric about both diagonal and antidiagonal, with all rows summing to n. 0
1, 921184, 52745205240, 367381371180384, 514918876680042334, 195842622547532763968 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..5.

CROSSREFS

Sequence in context: A256903 A185532 A321323 * A251954 A098208 A251172

Adjacent sequences:  A156425 A156426 A156427 * A156429 A156430 A156431

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 09 2009

STATUS

approved

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Last modified September 28 08:27 EDT 2022. Contains 357068 sequences. (Running on oeis4.)