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 A061044 Denominator of 1/25 - 1/n^2. 6

%I

%S 1,900,1225,1600,2025,100,3025,3600,4225,4900,225,6400,7225,8100,9025,

%T 80,11025,12100,13225,14400,625,16900,18225,19600,21025,180,24025,

%U 25600,27225,28900,1225,32400,34225,36100,38025,1600,42025

%N Denominator of 1/25 - 1/n^2.

%H Reinhard Zumkeller, <a href="/A061044/b061044.txt">Table of n, a(n) for n = 5..10000</a>

%H A. H. Pfund, <a href="https://doi.org/10.1364/JOSA.9.000193">The emission of nitrogen and hydrogen in the infrared</a>, Journal of the 0ptical Society of America, Vol. 9, Issue 3, (1924) pp. 193-196.

%t Table[Denominator[1/5^2 - 1/n^2], {n, 7, 50}] (* _G. C. Greubel_, Jul 07 2017 *)

%o (PARI) a(n) = denominator(1/25 - 1/n^2); \\ _Michel Marcus_, Aug 15 2013

%o import Data.Ratio ((%), denominator)

%o a061044 = denominator . (1 % 25 -) . recip . (^ 2) . fromIntegral

%o -- _Reinhard Zumkeller_, Jan 06 2014

%Y Cf. A061043 (numerator).

%K nonn,frac

%O 5,2

%A _N. J. A. Sloane_, May 26 2001

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Last modified August 3 10:43 EDT 2021. Contains 346435 sequences. (Running on oeis4.)