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Search: id:A077021
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| A077021 |
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a(n) is the unique odd positive solution y of 2^n = 7x^2+y^2. |
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4
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| 1, 3, 5, 1, 11, 9, 13, 31, 5, 57, 67, 47, 181, 87, 275, 449, 101, 999, 797, 1201, 2795, 393, 5197, 5983, 4411, 16377, 7555, 25199, 40309, 10089, 90707, 70529, 110885, 251943, 30173, 473713, 534059, 413367, 1481485, 654751, 2308219, 3617721
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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A. Engel, Problem-Solving Strategies. p. 126.
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LINKS
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Eric Weisstein's World of Mathematics, Diophantine Equations 2nd Powers
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FORMULA
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A077021(n+1)=Abs[A002249(n)] [From Artur Jasinski (grafix(AT)csl.pl), Oct 05 2008]
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MATHEMATICA
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a = {}; Do[k = Expand[((1 + I Sqrt[7])/2)^n + ((1 - I Sqrt[7])/2)^n]; AppendTo[a, Abs[k]], {n, 1, 50}]; a [From Artur Jasinski (grafix(AT)csl.pl), Oct 05 2008]
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CROSSREFS
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Cf. A077020.
a(n)=abs(A002249(n)).
Sequence in context: A101035 A026253 A138259 this_sequence A143250 A084833 A069111
Adjacent sequences: A077018 A077019 A077020 this_sequence A077022 A077023 A077024
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KEYWORD
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nonn
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AUTHOR
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Ed Pegg Jr. (ed(AT)mathpuzzle.com), Oct 17, 2002
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