OFFSET
7,2
COMMENTS
a(n) = (n+7)^2-49 = n*(n+14) = A098848(n), except a(7p). The corresponding series of atomic transitions is named Hansen-Strong. It comes after Lyman (1906-1914), Balmer (1885), Paschen (1908), Brackett (1922), Pfund (1924) and Humphreys series (1952 not 1953, justified later). - Paul Curtz, Oct 07 2008
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 7..1000
Peter Hansen and John Strong, Seventh Series of Atomic Hydrogen, Applied Optics, vol 12, 2, (Feb 1973), pp. 429-430. [From Paul Curtz, Oct 07 2008]
MATHEMATICA
Table[Numerator[1/49-1/n^2], {n, 7, 70}] (* Harvey P. Dale, Apr 26 2016 *)
PROG
(PARI) a(n) = numerator(1/49 - 1/n^2); \\ Michel Marcus, Aug 15 2013
(Magma) [Numerator(1/49-1/n^2): n in [7..60]]; // Vincenzo Librandi, Sep 07 2016
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
N. J. A. Sloane, May 26 2001
EXTENSIONS
Edited by M. F. Hasler, Nov 17 2014
STATUS
approved