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A059138 A hierarchical sequence (S(W3{2,2}cc) - see A059126). 0
18, 90, 270, 666, 1494, 3186, 6606, 13482, 27270, 54882, 110142, 220698, 441846, 884178, 1768878 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..14.

J. Wallgren, Hierarchical sequences

FORMULA

Conjectures from Colin Barker, Oct 07 2015: (Start)

a(n) = 18*(-5+3*2^(1+n)-2*n) = 18*A050488(n+1).

a(n) = 4*a(n-1)-5*a(n-2)+2*a(n-3) for n>2.

G.f.: -18*(x+1) / ((x-1)^2*(2*x-1)).

(End)

CROSSREFS

Sequence in context: A063788 A066854 A247901 * A117735 A041624 A227812

Adjacent sequences:  A059135 A059136 A059137 * A059139 A059140 A059141

KEYWORD

easy,nonn,more

AUTHOR

Jonas Wallgren, Jan 19 2001

STATUS

approved

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Last modified January 23 23:56 EST 2021. Contains 340398 sequences. (Running on oeis4.)