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A083869
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a(1)=1 then a(n) is the least k>=1 such that the nested radical sqrt(a(1)^2+sqrt(a(2)^2+sqrt(a(3)^2+(....+sqrt(a(n)^2)))...) is an integer.
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5
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1, 3, 55, 43631, 99515655135, 4723258824886629604131775, 589359179694820074404152604620573424809709490316113791, 13331474848620898858862175943355927686887898121894707763190978243005066121710225087713374054319814910927464555589375
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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FORMULA
| n = sqrt(a(1)^2+sqrt(a(2)^2+sqrt(a(3)^2+(....+sqrt(a(n)^2)))...)
Equals main diagonal of triangle A166994. [From Paul D. Hanna (pauldhanna(AT)juno.com), Nov 18 2009]
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MAPLE
| k=55 is the least integer such that sqrt(1^2+sqrt(3^2+sqrt(k^2)))=3 is an integer hence a(3)=55.
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CROSSREFS
| Cf. A166994. [From Paul D. Hanna (pauldhanna(AT)juno.com), Nov 18 2009]
Sequence in context: A172950 A172962 A110058 * A119188 A111451 A198184
Adjacent sequences: A083866 A083867 A083868 * A083870 A083871 A083872
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 18 2003
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