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Search: id:A048871
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| A048871 |
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Length of hypotenuse squared in right triangle formed by a palindromic spiral plotted in cartesian coordinates. |
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+0
1
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| 2, 5, 13, 25, 41, 61, 85, 113, 145, 202, 605, 1573, 3025, 4961, 7381, 10285, 13673, 17545, 20002, 22522, 26962, 31802, 37042, 42682, 48722, 55162, 62002, 69242, 77285, 85748, 94228, 103108, 112388, 122068, 132148, 142628, 153508, 164788
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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H. E. Huntley, The Divine Proportion, A Study in Mathematical Beauty. New York: Dover, 1970. See Chapter 13, Spira Mirabilis, especially Fig. 13-5, page 173.
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LINKS
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P. De Geest, World!Of Numbers
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FORMULA
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To begin palindromic spiral, plot (1, 0), (0, 1). Hypotenuse is c^2=a^2+b^2, or 2=1+1. a(1) = 2.
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EXAMPLE
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a(2)=5 because c^2=a^2+b^2 and 5=1+4.
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CROSSREFS
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An analogue of the prime spiral of A048851.
A048871(n)=A002113(n)^2+A002113(n-1)^2, n>1.
Sequence in context: A049779 A106009 A079780 this_sequence A072921 A087250 A065301
Adjacent sequences: A048868 A048869 A048870 this_sequence A048872 A048873 A048874
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KEYWORD
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easy,nonn,nice
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AUTHOR
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Enoch Haga (Enokh(AT)comcast.net)
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