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A024508
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Numbers that are a sum of 2 distinct nonzero squares in more than one way.
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6
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65, 85, 125, 130, 145, 170, 185, 205, 221, 250, 260, 265, 290, 305, 325, 340, 365, 370, 377, 410, 425, 442, 445, 481, 485, 493, 500, 505, 520, 530, 533, 545, 565, 580, 585, 610, 625, 629, 650, 680, 685, 689, 697, 725, 730, 740, 745, 754, 765, 785, 793, 820
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Appears to be n such that sigma(n)==0 (mod 4) and n is expressible as a sum of 2 squares. - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 20 2003
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LINKS
| Index entries for sequences related to sums of squares
G. Xiao, Two squares
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MATHEMATICA
| lst={}; q=-1; k=1; Do[Do[x=a^2; Do[y=b^2; If[x+y==n, If[n==q&&k==1, AppendTo[lst, n]]; If[n!=q, q=n; k=1, k++ ]], {b, Floor[(n-x)^(1/2)], a+1, -1}], {a, Floor[n^(1/2)], 1, -1}], {n, 2*6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 22 2009]
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CROSSREFS
| Cf. A001481.
Sequence in context: A056693 A164282 A025312 * A025303 A071011 A165158
Adjacent sequences: A024505 A024506 A024507 * A024509 A024510 A024511
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KEYWORD
| nonn
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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