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A045695 Number of ternary words of length n (beginning 0) with autocorrelation function 2^(n-1)+1. 1
0, 1, 2, 8, 22, 70, 202, 622, 1844, 5576, 16658, 50114, 150140, 450824, 1351850, 4056794, 12168538, 36509302, 109522330, 328578142, 985717768, 2957186620, 8871509746, 26614629466, 79843738258, 239531515054, 718594094338 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..27.

FORMULA

a(2n) = 3*a(2n-1) + 2*a(n) for n >= 2; a(2n-1) = 3*a(2n-2) - a(n) for n >= 2

MAPLE

A045695 := proc(n)

    if n <=2 then

        n-1 ;

    elif type(n, 'even') then

        3*procname(n-1)+2*procname(n/2) ;

    else

        3*procname(n-1)-procname((n+1)/2) ;

    end if;

end proc: # R. J. Mathar, Oct 04 2014

CROSSREFS

Sequence in context: A321573 A137103 A089586 * A106053 A121135 A183410

Adjacent sequences:  A045692 A045693 A045694 * A045696 A045697 A045698

KEYWORD

nonn

AUTHOR

TORSTEN.SILLKE(AT)LHSYSTEMS.COM

STATUS

approved

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Last modified December 13 15:03 EST 2018. Contains 318086 sequences. (Running on oeis4.)