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%I #8 Nov 23 2015 01:35:21
%S 1,4,15,49,172,511,1600,4968,15328,40858,82484,106963,114376,116592,
%T 117100,117127,117128,117129
%N Number of stars brighter than visual magnitude n-1.
%C These numbers are not well-defined and the sequence is included only for completeness.
%C The visual magnitude (m) scale is logarithmic: for two stars of brightness i1 and i2 (as seen from the Earth), the magnitude difference m1 - m2 = - log(i1/i2)*100^(1/5). Fainter stars have a higher magnitude number. Data collected by the Hipparcos satellite and exhaustive up to about 9 mag (n=10). At fainter magnitudes (n > 10), the data are increasingly fragmentary (thus the slowing rate of increase from there).
%H Author?, <a href="http://astro.estec.esa.nl/Hipparcos/">Source</a> [Broken link?]
%H Author?, <a href="http://euclid.tp.ph.ic.ac.uk/~albrecht/college-only/astro-notes-old/astro-notes/node106.html">Source</a> [Broken link?]
%F a(n) would be proportional to 10^(0.6*n) in the simplifying hypothesis of a uniform distribution of identical stars in an infinite universe. Any empirical formula matching the actual sequence for n=0 to 10 is welcome.
%e There is 1 star brighter than -1 mag (Sirius, -1.44 mag). There are 4968 stars brighter than 6 mag, which is about the faintest brightness visible to the naked eye.
%Y Cf. A072171.
%K nonn,dumb
%O 0,2
%A Jean Fontaine (jfontain(AT)odyssee.net), Jan 08 2000
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