OFFSET
3,2
COMMENTS
Is the number 0.77141814577... rational? Note groups of 4,1,8 at positions 7, 16, 25, 34, 43 etc.; also 7,7 positions 4, 13, 21, 31, 40, 49 etc.
From Paschen spectrum of hydrogen.
The number 6 appears at positions n=84, 159, 327, 402 etc.; the number 3 at n=78, 165, 321 etc; the number 0 at n=3, 240, 246 etc. - R. J. Mathar, Feb 28 2009
Starting with a(7) the pattern {4, 1, 8, 1, 4, b(n), 7, 7, c(n)} is repeated with b(n) and c(n) containing numbers zero to nine. - G. C. Greubel, Mar 08 2022
LINKS
G. C. Greubel, Table of n, a(n) for n = 3..5000
FORMULA
a(n) = A061039(n) mod 9.
MATHEMATICA
Mod[Numerator[1/9 - 1/(Range[3, 150])^2], 9] (* G. C. Greubel, Mar 08 2022 *)
PROG
(Sage) [numerator(1/9 - 1/n^2)%9 for n in (3..150)] # G. C. Greubel, Mar 08 2022
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Paul Curtz, Oct 30 2008
STATUS
approved