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A159367
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Number of n X n arrays of squares of integers summing to 7
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1
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4, 540, 18720, 531300, 8583300, 86748088, 623757696, 3483871560, 16023245700, 63174296020, 219752181792, 688950636972, 1978607887620, 5271705817200, 13162584962560, 31050835145616, 69671782148868, 149524133455500
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OFFSET
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2,1
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COMMENTS
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All such sequences have holonomic recurrences (cf. comment in A159359). - Georg Fischer, Feb 17 2022
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (15, -105, 455, -1365, 3003, -5005, 6435, -6435, 5005, -3003, 1365, -455, 105, -15, 1).
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FORMULA
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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]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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