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Triangle T(m,n) = numerator of 1/m^2 - 1/n^2, n >= 1, m=n,n-1,n-2,...,1.
18

%I #17 Jun 04 2013 04:17:13

%S 0,0,3,0,5,8,0,7,3,15,0,9,16,21,24,0,11,5,1,2,35,0,13,24,33,40,45,48,

%T 0,15,7,39,3,55,15,63,0,17,32,5,56,65,8,77,80,0,19,9,51,4,3,21,91,6,

%U 99,0,21,40,57,72,85,96,105,112,117,120,0,23,11,7,5,95,1,119,1,5,35,143,0

%N Triangle T(m,n) = numerator of 1/m^2 - 1/n^2, n >= 1, m=n,n-1,n-2,...,1.

%C Wavelengths in hydrogen spectrum are given by Rydberg's formula 1/wavelength = constant*(1/m^2 - 1/n^2).

%D J. E. Brady and G. E. Humiston, General Chemistry, 3rd. ed., Wiley; p. 77.

%H Reinhard Zumkeller, <a href="/A061035/b061035.txt">Rows n=1..100 of triangle, flattened</a>

%H J. J. O'Connor and E. F. Robertson, <a href="http://www-groups.dcs.st-andrews.ac.uk/~history/Mathematicians/Rydberg.html">Johannes Robert Rydberg</a>

%H Eric Weisstein's World of Physics, <a href="http://scienceworld.wolfram.com/physics/BalmerFormula.html">Balmer Formula</a>

%e Triangle 1/m^2-1/n^2, m >= 1, 1<=n<=m, (i.e. with rows reversed) begins

%e 0

%e 3/4, 0

%e 8/9, 5/36, 0

%e 15/16, 3/16, 7/144, 0

%e 24/25, 21/100, 16/225, 9/400, 0

%e 35/36, 2/9, 1/12, 5/144, 11/900, 0

%t t[m_, n_] := Numerator[1/m^2 - 1/n^2]; Table[t[m, n], {n, 1, 12}, {m, n, 1, -1}] // Flatten(* _Jean-François Alcover_, Oct 17 2012 *)

%o (Haskell)

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

%o a061035 n k = a061035_tabl !! (n-1) !! (k-1)

%o a061035_row = map numerator . balmer where

%o balmer n = map (subtract (1 % n ^ 2) . (1 %) . (^ 2)) [n, n-1 .. 1]

%o a061035_tabl = map a061035_row [1..]

%o -- _Reinhard Zumkeller_, Apr 12 2012

%Y Cf. A061036. Rows give A061037-A061050.

%Y Cf. A126252.

%K nonn,tabl,easy,nice,frac

%O 1,3

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

%E More terms from _Naohiro Nomoto_, Jul 15 2001