A059138 A hierarchical sequence (S(W3{2,2}cc) - see A059126).

18, 90, 270, 666, 1494, 3186, 6606, 13482, 27270, 54882, 110142, 220698, 441846, 884178, 1768878, 3538314, 7077222, 14155074, 28310814, 56622330, 113245398, 226491570, 452983950, 905968746, 1811938374, 3623877666, 7247756286, 14495513562, 28991028150

Offset

0,1

Links

Table of n, a(n) for n=0..28.

Jonas Wallgren, Hierarchical sequences

Index entries for linear recurrences with constant coefficients, signature (4, -5, 2).

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

Cf. A059126.

Sequence in context: A066854 A247901 A369419 * A117735 A041624 A227812

Adjacent sequences: A059135 A059136 A059137 * A059139 A059140 A059141

Keyword

nonn

Author

Jonas Wallgren, Jan 19 2001

Extensions

More terms from Sean A. Irvine, Sep 13 2022

Status

approved