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

1, 900, 1225, 1600, 2025, 100, 3025, 3600, 4225, 4900, 225, 6400, 7225, 8100, 9025, 80, 11025, 12100, 13225, 14400, 625, 16900, 18225, 19600, 21025, 180, 24025, 25600, 27225, 28900, 1225, 32400, 34225, 36100, 38025, 1600, 42025

Offset: 5

Author

N. J. A. Sloane, May 26 2001

Keywords

• nonn
• frac

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 5..10000
• A. H. Pfund, The emission of nitrogen and hydrogen in the infrared, Journal of the Optical Society of America, Vol. 9, Issue 3, (1924) pp. 193-196.

Crossrefs

See A061041 for comments, references, links.

Cf. A061043 (numerator).

Programs

Haskell

import Data.Ratio ((%), denominator)
a061044 = denominator . (1 % 25 -) . recip . (^ 2) . fromIntegral
-- Reinhard Zumkeller, Jan 06 2014

Mathematica

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

PARI

a(n) = denominator(1/25 - 1/n^2); \\ Michel Marcus, Aug 15 2013