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A159367 Number of n X n arrays of squares of integers summing to 7 1
4, 540, 18720, 531300, 8583300, 86748088, 623757696, 3483871560, 16023245700, 63174296020, 219752181792, 688950636972, 1978607887620, 5271705817200, 13162584962560, 31050835145616, 69671782148868, 149524133455500 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

R. H. Hardin, Table of n, a(n) for n=2..100

FORMULA

Empirical: a(n)=n^2*(n-1)*(n+1)*(n^2-2)*(n^2-3)*(n^6-15*n^4+74*n^2+720)/5040. [From R. J. Mathar, Aug 11 2009]

CROSSREFS

Sequence in context: A152463 A295206 A209608 * A012770 A332154 A202032

Adjacent sequences:  A159364 A159365 A159366 * A159368 A159369 A159370

KEYWORD

nonn

AUTHOR

R. H. Hardin Apr 11 2009

STATUS

approved

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Last modified May 23 00:47 EDT 2022. Contains 353959 sequences. (Running on oeis4.)