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A061039
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Numerator of 1/9 - 1/n^2.
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32
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0, 7, 16, 1, 40, 55, 8, 91, 112, 5, 160, 187, 8, 247, 280, 35, 352, 391, 16, 475, 520, 7, 616, 667, 80, 775, 832, 11, 952, 1015, 40, 1147, 1216, 143, 1360, 1435, 56, 1591, 1672, 65, 1840, 1927, 224, 2107, 2200, 85, 2392, 2491, 32, 2695, 2800
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,2
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COMMENTS
| From Paschen spectrum of hydrogen. Wavelengths in hydrogen spectrum are given by Rydberg's formula 1/wavelength = constant*(1/m^2 - 1/n^2).
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REFERENCES
| J. E. Brady and G. E. Humiston, General Chemistry, 3rd. ed., Wiley; p. 78.
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LINKS
| J. J. O'Connor and E. F. Robertson, Johannes Robert Rydberg
Eric Weisstein's World of Physics, Balmer Formula
Reinhard Zumkeller, Table of n, a(n) for n = 3..1000
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FORMULA
| a(n) <= n^2-9; if n is not divisible by 3 then a(n) = n^2-9 - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 16 2006
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MATHEMATICA
| Table[Numerator[1/9 - 1/n^2], {n, 3, 60}] (* Stefan Steinerberger, Apr 16 2006 *)
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PROG
| (Haskell)
import Data.Ratio ((%), numerator)
a061039 n = numerator $ 1%9 - 1%n ^ 2 -- Reinhard Zumkeller, Jan 03 2012
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CROSSREFS
| Cf. A061035-A061050.
Sequence in context: A087485 A156377 A069526 * A063593 A070417 A101681
Adjacent sequences: A061036 A061037 A061038 * A061040 A061041 A061042
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KEYWORD
| nonn,frac,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), May 26 2001
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