The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A215666 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A215666

a(n) = 3*a(n-2) - a(n-3), with a(0)=0, a(1)=-3, and a(2)=6.
(history; published version)

#23 by N. J. A. Sloane at Thu Jun 16 23:27:48 EDT 2016

REFERENCES

R. Witula, Ramanujan type formulae formulas for arguments 2Pi/7 and 2Pi/9, Demonstratio Math., (in press, 2012).

Discussion

Thu Jun 16

23:27

OEIS Server: https://oeis.org/edit/global/2523

#22 by Ray Chandler at Sat Aug 01 10:35:23 EDT 2015

STATUS

editing

approved

#21 by Ray Chandler at Sat Aug 01 10:35:17 EDT 2015

LINKS

<a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0, 3, -1).

STATUS

approved

editing

#20 by Charles R Greathouse IV at Mon Oct 01 10:53:52 EDT 2012

STATUS

editing

approved

#19 by Charles R Greathouse IV at Mon Oct 01 10:53:50 EDT 2012

PROG

(PARI) concat(0, Vec(-3*(1-2*x)/(1-3*x^2+x^3)+O(x^99))) \\ Charles R Greathouse IV, Oct 01 2012

KEYWORD

sign,easy

STATUS

approved

editing

#18 by T. D. Noe at Mon Aug 27 12:13:31 EDT 2012

STATUS

proposed

approved

#17 by Roman Witula at Mon Aug 27 08:24:31 EDT 2012

STATUS

editing

proposed

#16 by Roman Witula at Mon Aug 27 08:24:25 EDT 2012

COMMENTS

If we set X(n) = 3*X(n-2) - X(n-3), n in Z, then with a(n) = X(n) and , for every n=0,1,..., then X(-n) = -abs(A215917(n)) = (-1)^n*A215917(n), for every n=0,1,...

STATUS

proposed

editing

#15 by Roman Witula at Mon Aug 27 08:11:15 EDT 2012

STATUS

editing

proposed

#14 by Roman Witula at Mon Aug 27 08:11:08 EDT 2012

COMMENTS

If we set X(n) = 3*X(n-2) - X(n-3), n in Z, then a(n) = X(n) and X(-n) = -abs(A215917(n)) = (-1)^n*A215917(n), for every n=0,1,...

STATUS

approved

editing