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A115335 a(0)=3, a(1)=5, a(2)=1, and a(n) = (2^(1+n)-11*(-1)^n)/3 for n>2. 0
3, 5, 1, 9, 7, 25, 39, 89, 167, 345, 679, 1369, 2727, 5465, 10919, 21849, 43687, 87385, 174759, 349529, 699047, 1398105, 2796199, 5592409, 11184807, 22369625, 44739239, 89478489, 178956967, 357913945, 715827879, 1431655769, 2863311527, 5726623065, 11453246119, 22906492249, 45812984487 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Old name was: a(n) = 2*Abs[(1/2)*(-1+(-2)^n)-(2/3)*(2+(-2)^n)*UnitStep[ -1+n]].

LINKS

Table of n, a(n) for n=0..36.

Index entries for linear recurrences with constant coefficients, signature (1,2).

FORMULA

a(n) = a(n-1)+2*a(n-2) for n>4. G.f.: (4*x^4+2*x^3+10*x^2-2*x-3) / ((x+1)*(2*x-1)). [Colin Barker, Jan 04 2013]

MATHEMATICA

Join[{3, 5, 1}, LinearRecurrence[{1, 2}, {9, 7}, 40]] (* Harvey P. Dale, Jul 17 2014 *)

CROSSREFS

Sequence in context: A228146 A241674 A021970 * A214062 A054586 A214229

Adjacent sequences:  A115332 A115333 A115334 * A115336 A115337 A115338

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Mar 06 2006

EXTENSIONS

a(24) corrected, new name, and editing by Colin Barker and Joerg Arndt, Jan 04 2013

STATUS

approved

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Last modified March 27 02:08 EDT 2017. Contains 284143 sequences.