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A057356 a(n) = floor(2*n/7). 16
0, 0, 0, 0, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 22, 22, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,8
COMMENTS
The cyclic pattern (and numerator of the gf) is computed using Euclid's algorithm for GCD.
REFERENCES
R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, Addison-Wesley, NY, 1994.
N. Dershowitz and E. M. Reingold, Calendrical Calculations, Cambridge University Press, 1997.
LINKS
N. Dershowitz and E. M. Reingold, Calendrical Calculations Web Site.
FORMULA
G.f.: x^4*(1+x)*(x^2-x+1)/( (x^6+x^5+x^4+x^3+x^2+x+1)*(x-1)^2 ). - Numerator corrected by R. J. Mathar, Feb 20 2011
Sum_{n>=4} (-1)^n/a(n) = Pi/4 (A003881). - Amiram Eldar, Sep 30 2022
MATHEMATICA
Table[Floor[2*n/7], {n, 0, 50}] (* G. C. Greubel, Nov 03 2017 *)
PROG
(PARI) a(n)=2*n\7 \\ Charles R Greathouse IV, Sep 24 2015
(Magma) [Floor(2*n/7): n in [0..50]]; // G. C. Greubel, Nov 03 2017
CROSSREFS
Cf. A003881.
Sequence in context: A269734 A066927 A060065 * A172274 A350843 A183138
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)