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A342903
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a(n) is the smallest number that is the sum of n positive squares in two ways.
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10
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50, 27, 28, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86
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OFFSET
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2,1
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COMMENTS
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This is r(n,2,2) in Alter's notation.
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LINKS
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Table of n, a(n) for n=2..71.
R. Alter, Computations and generalizations on a remark of Ramanujan, pp. 182-196 of "Analytic Number Theory (Philadelphia, 1980)", ed. M. I. Knopp, Lect. Notes Math., Vol. 899, 1981. See Eq. (15), page 188.
Index entries for linear recurrences with constant coefficients, signature (2,-1).
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FORMULA
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a(n) = n+15 for n >= 5.
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EXAMPLE
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a(2) = 50 = 1+49 = 25+25.
a(3) = 27 = 1+1+25 = 9+9+9.
a(5) = 20 = 1+1+1+1+16 = 4+4+4+4+4.
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CROSSREFS
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Cf. A230563, A342902.
Sequence in context: A033370 A090691 A033980 * A207149 A207142 A244277
Adjacent sequences: A342900 A342901 A342902 * A342904 A342905 A342906
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Apr 03 2021
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STATUS
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approved
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