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 A261915 Smallest x such that n can be written as n = x^2 + y^2 + z^2 with x >= y >= z >= 0, or -1 if no such x exists. 4
 0, 1, 1, 1, 2, 2, 2, -1, 2, 2, 3, 3, 2, 3, 3, -1, 4, 3, 3, 3, 4, 4, 3, -1, 4, 4, 4, 3, -1, 4, 5, -1, 4, 4, 4, 5, 4, 6, 5, -1, 6, 4, 5, 5, 6, 5, 6, -1, 4, 6, 5, 5, 6, 6, 5, -1, 6, 5, 7, 5, -1, 6, 6, -1, 8, 6, 5, 7, 6, 7, 6, -1, 6, 6, 7, 5, 6, 6, 7, -1, 8, 6, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS a(n) = -1 iff n is in A004215, a(n) >= 0 iff n is in A000378. If we maximize x we get A261904. LINKS David Consiglio, Jr., Table of n, a(n) for n = 0..10000 David Consiglio, Jr., Python Program EXAMPLE Table showing initial values of n,x,y,z:    0  0  0  0    1  1  0  0    2  1  1  0    3  1  1  1    4  2  0  0    5  2  1  0    6  2  1  1    7 -1 -1 -1    8  2  2  0    9  2  2  1   10  3  1  0   11  3  1  1   12  2  2  2   13  3  2  0   14  3  2  1   15 -1 -1 -1   16  4  0  0   17  3  2  2   18  3  3  0   19  3  3  1   20  4  2  0   ... CROSSREFS Cf. A000378, A004215, A005875, A261904. Analogs for 4 squares: A178786 and A122921. Sequence in context: A083338 A241900 A204018 * A109037 A147680 A192895 Adjacent sequences:  A261912 A261913 A261914 * A261916 A261917 A261918 KEYWORD sign AUTHOR N. J. A. Sloane, Sep 11 2015 EXTENSIONS a(17) corrected, more terms from David Consiglio, Jr., Sep 11 2015 STATUS approved

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Last modified August 22 07:40 EDT 2019. Contains 326172 sequences. (Running on oeis4.)