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a(n) = floor(3*n/5).
17

%I #36 Dec 30 2023 23:52:38

%S 0,0,1,1,2,3,3,4,4,5,6,6,7,7,8,9,9,10,10,11,12,12,13,13,14,15,15,16,

%T 16,17,18,18,19,19,20,21,21,22,22,23,24,24,25,25,26,27,27,28,28,29,30,

%U 30,31,31,32,33,33,34,34,35,36,36,37,37,38,39,39,40,40,41,42,42,43,43

%N a(n) = floor(3*n/5).

%C The cyclic pattern (and numerator of the gf) is computed using Euclid's algorithm for GCD.

%C The sequence can be obtained from A008588 by deleting the last digit of each term. - _Bruno Berselli_, Sep 11 2019

%D N. Dershowitz and E. M. Reingold, Calendrical Calculations, Cambridge University Press, 1997.

%D R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, Addison-Wesley, NY, 1994.

%H G. C. Greubel, <a href="/A057355/b057355.txt">Table of n, a(n) for n = 0..5000</a>

%H N. Dershowitz and E. M. Reingold, <a href="http://emr.cs.iit.edu/home/reingold/calendar-book/first-edition/">Calendrical Calculations Web Site</a>.

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,1,-1).

%F G.f.: x^2*(1 + x^2 + x^3)/((1 - x)*(1 - x^5)). - Bruce Corrigan (scentman(AT)myfamily.com), Jul 03 2002

%F For all m>=0: a(5m)=0 mod 3; a(5m+1)=0 mod 3; a(5m+2)=1 mod 3; a(5m+3)=1 mod 3; a(5m+4)=2 mod 3.

%F Sum_{n>=2} (-1)^n/a(n) = Pi/(3*sqrt(3)) - log(2)/3. - _Amiram Eldar_, Sep 30 2022

%t Table[Floor[3*n/5], {n, 0, 50}] (* _G. C. Greubel_, Nov 02 2017 *)

%o (PARI) a(n)=3*n\5 \\ _Charles R Greathouse IV_, Sep 02 2015

%o (Magma) [3*n div 5: n in [0..80]]; // _Bruno Berselli_, Dec 07 2016

%Y Floors of other ratios: A004526, A002264, A002265, A004523, A057353, A057354, A057355, A057356, A057357, A057358, A057359, A057360, A057361, A057362, A057363, A057364, A057365, A057366, A057367.

%Y Cf. A008588.

%K nonn,easy

%O 0,5

%A _Mitch Harris_