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A161882
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Smallest k such that n^2 = a_1^2+...+a_k^2 and all a_i are positive integers less than n.
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4
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4, 3, 4, 2, 3, 3, 4, 3, 2, 3, 3, 2, 3, 2, 4, 2, 3, 3, 2, 3, 3, 3, 3, 2, 2, 3, 3, 2, 2, 3, 4, 3, 2, 2, 3, 2, 3, 2, 2, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| Related to hypotenuse numbers: A161882(A009003(n))=2 for all n.
Jacobi's four-square theorem can be used to show that a(n) <= 4. [Charles R Greathouse IV, Jul 31 2011]
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LINKS
| Jean-Charles Meyrignac, Computing minimal equal sums of like powers
Weisstein, Eric W., Diophantine Equation 2nd Powers
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EXAMPLE
| 2^2 = 1^2 + 1^2 + 1^2 + 1^2, so a(2)=4. 3^2 = 2^2 + 2^2 + 1^2, so a(3)=3.
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CROSSREFS
| Cf. A161883, A161884, A161885.
Sequence in context: A170987 A196826 A204819 * A082125 A058290 A002285
Adjacent sequences: A161879 A161880 A161881 * A161883 A161884 A161885
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KEYWORD
| nonn
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AUTHOR
| Dmitry Kamenetsky (dkamen(AT)rsise.anu.edu.au), Jun 21 2009
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