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A004441
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Numbers that are not the sum of 4 distinct nonzero squares.
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4
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1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 47, 48, 49, 52, 53, 55, 56, 58, 59, 60, 61, 64, 67, 68
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| It has been shown that 157 is the last odd number in this sequence. Beyond 157, the terms grow exponentially. - T. D. Noe, Apr 07 2007
Taking a(86) to a(120) as initial terms, A004441(n) satisfies the thirty fifth order recurrence relation u(n)=4u(n-35) [From Ant King (mathstutoring(AT)ntlworld.com), Aug 13 2010]
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REFERENCES
| Paul T. Bateman, Adolf J. Hildebrand and George B. Purdy, Sums of distinct squares. Acta Arith. 67 (1994), 349-380.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..1000 (using A004195 and A004196)
Index entries for sequences related to sums of squares
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MATHEMATICA
| data1=Reduce[w^2+x^2+y^2+z^2==# && 0<w<x<y<z<#, {w, x, y, z}, Integers]&/@Range[1000]; data2=If[Head[ # ]===And, 1, Length[ # ]] &/@data1; DeleteCases[Table[If[data2[[k]]>0, 0, k], {k, 1, Length[data2]}], 0] [From Ant King (mathstutoring(AT)ntlworld.com), Aug 13 2010]
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CROSSREFS
| Cf. A004195, A004196.
Sequence in context: A160547 A192218 A070915 * A004438 A109425 A153679
Adjacent sequences: A004438 A004439 A004440 * A004442 A004443 A004444
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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