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A003143 a(2*n) = floor( 17*2^n/14 ), a(2*n+1) = floor( 12*2^n/7 ).
(Formerly M0570)
1
1, 1, 2, 3, 4, 6, 9, 13, 19, 27, 38, 54, 77, 109, 155, 219, 310, 438, 621, 877, 1243, 1755, 2486, 3510, 4973, 7021, 9947, 14043, 19894, 28086, 39789, 56173, 79579, 112347, 159158, 224694, 318317, 449389, 636635, 898779, 1273270, 1797558 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

REFERENCES

D. E. Knuth, The Art of Computer Programming. Addison-Wesley, Reading, MA, Vol. 3, p. 207.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992.

Simon Plouffe, 1031 Generating Functions and Conjectures, Université du Québec à Montréal, 1992.

FORMULA

a(n) = a(n-1) + a(n-2) - a(n-3) + a(n-4) - a(n-5) + 2*a(n-6) - 2*a(n-7) for n > 7. - Chai Wah Wu, May 25 2016

MAPLE

A003143:=(1+z**3-z**4+z**5-z**6+z**7)/((z-1)*(z**2-z+1)*(z**2+z+1)*(2*z**2-1)); # [Conjectured (correctly) by Simon Plouffe in his 1992 dissertation.]

MATHEMATICA

Flatten[Table[{Floor[17 2^n / 14], Floor[12 2^n / 7]}, {n, 0, 30}]] (* Vincenzo Librandi, May 27 2016 *)

PROG

(PARI) a(n)=(17+7*(n%2))*2^(n\2)\14

(MAGMA) [(17+7*(n mod 2))*2^(n div 2) div 14: n in [0..50]]; // Vincenzo Librandi, May 27 2016

CROSSREFS

Sequence in context: A017824 A094054 A001521 * A221718 A251571 A017983

Adjacent sequences:  A003140 A003141 A003142 * A003144 A003145 A003146

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Michael Somos, May 04 2000

STATUS

approved

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Last modified September 20 03:28 EDT 2020. Contains 337264 sequences. (Running on oeis4.)