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%I #23 Aug 21 2017 05:49:37
%S 0,1,1,1,1,1,0,1,1,1,0,1,0,1,1,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,1,1,
%T 1,1,0,1,1,1,0,1,0,1,1,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,1,1,1,1,0,1,
%U 1,1,0,1,0,1,1,0,0,1,0,1,0,0,0,1,0,0,0,0
%N a(n) = floor(n) - floor(n/2) - floor(n/3) - floor(n/5) + floor(n/30).
%C The sequence takes only the values 0 and 1 and is periodic with period 30. The sequence was used by Chebyshev to obtain the estimate for the prime counting function 0.92*x/log(x) <= #{primes <= x} <= 1.11*x/log(x), for x sufficiently large.
%H G. C. Greubel, <a href="/A182067/b182067.txt">Table of n, a(n) for n = 0..1000</a>
%H H. G. Diamond, <a href="https://doi.org/10.1090/S0273-0979-1982-15057-1">Elementary methods in the study of the distribution of prime numbers</a>, Bull. Amer. Math. Soc., Vol.7 (3), 1982.
%H <a href="/index/Rec#order_30">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).
%t Table[Floor[n] - Floor[n/2] - Floor[n/3] - Floor[n/5] + Floor[n/30], {n,0,50}] (* _G. C. Greubel_, Aug 20 2017 *)
%o (PARI) a(n) = n - n\2 - n\3 - n\5 + n\30; \\ _Michel Marcus_, Jul 25 2017
%Y Cf. A211417.
%K nonn,easy
%O 0
%A _Peter Bala_, Apr 11 2012
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