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A hierarchical sequence (S(W3{2,2}cc) - see A059126).
0

%I #23 Jul 02 2023 16:10:26

%S 18,90,270,666,1494,3186,6606,13482,27270,54882,110142,220698,441846,

%T 884178,1768878,3538314,7077222,14155074,28310814,56622330,113245398,

%U 226491570,452983950,905968746,1811938374,3623877666,7247756286,14495513562,28991028150

%N A hierarchical sequence (S(W3{2,2}cc) - see A059126).

%H Jonas Wallgren, <a href="/A059126/a059126.txt">Hierarchical sequences</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (4, -5, 2).

%F Conjectures from _Colin Barker_, Oct 07 2015: (Start)

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

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

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

%F (End)

%Y Cf. A059126.

%K nonn

%O 0,1

%A _Jonas Wallgren_, Jan 19 2001

%E More terms from _Sean A. Irvine_, Sep 13 2022