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A007692
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Numbers that are the sum of 2 nonzero squares in 2 or more ways.
(Formerly M5299)
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10
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50, 65, 85, 125, 130, 145, 170, 185, 200, 205, 221, 250, 260, 265, 290, 305, 325, 338, 340, 365, 370, 377, 410, 425, 442, 445, 450, 481, 485, 493, 500, 505, 520, 530, 533, 545, 565, 578, 580, 585, 610, 625, 629, 650, 680, 685, 689, 697, 725, 730, 740, 745, 754, 765
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| A025426(a(n)) > 1. [Reinhard Zumkeller, Aug 16 2011]
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REFERENCES
| Ming-Sun Li, Kathryn Robertson, Thomas J. Osler, Abdul Hassen, Christopher S. Simons and Marcus Wright, "On numbers equal to the sum of two squares in more than one way", Mathematics and Computer Education, 43 (2009), 102 - 108. [From Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jul 27 2009]
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, 125.
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
AskNRICH Archive, Numbers expressible as the sum of 2 squares in more than one way
D. J. C. Mackay and S. Mahajan, Numbers that are Sums of Squares in Several Ways
G. Xiao, Two squares
Index entries for sequences related to sums of squares
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PROG
| (Haskell)
import Data.List (findIndices)
a007692 n = a007692_list !! (n-1)
a007692_list = findIndices (> 1) a025426_list
-- Reinhard Zumkeller, Aug 16 2011
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CROSSREFS
| Subsequence of A001481.
Cf. A004431, A118882, A000404, A018825, A025284.
Sequence in context: A179796 A109552 A206263 * A025285 A092541 A180103
Adjacent sequences: A007689 A007690 A007691 * A007693 A007694 A007695
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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