This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A059138 #23 Jul 02 2023 16:10:26
%S A059138 18,90,270,666,1494,3186,6606,13482,27270,54882,110142,220698,441846,
%T A059138 884178,1768878,3538314,7077222,14155074,28310814,56622330,113245398,
%U A059138 226491570,452983950,905968746,1811938374,3623877666,7247756286,14495513562,28991028150
%N A059138 A hierarchical sequence (S(W3{2,2}cc) - see A059126).
%H A059138 Jonas Wallgren, <a href="/A059126/a059126.txt">Hierarchical sequences</a>
%H A059138 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (4, -5, 2).
%F A059138 Conjectures from _Colin Barker_, Oct 07 2015: (Start)
%F A059138 a(n) = 18*(-5 + 3*2^(1+n) - 2*n) = 18*A050488(n+1).
%F A059138 a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3) for n>2.
%F A059138 G.f.: -18*(x+1) / ((x-1)^2*(2*x-1)).
%F A059138 (End)
%Y A059138 Cf. A059126.
%K A059138 nonn
%O A059138 0,1
%A A059138 _Jonas Wallgren_, Jan 19 2001
%E A059138 More terms from _Sean A. Irvine_, Sep 13 2022