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%I #25 Dec 11 2015 15:00:55
%S 1,6,18,54,162,486,1458,4374,13122,39366,118098,354294,1062882,
%T 3188646,9565938,28697814,86093442,258280326,774840978,2324522934,
%U 6973568802,20920706406,62762119218,188286357654,564859072962,1694577218886
%N Expansion of (1+3x)/(1-3x).
%C A099858 gives a Chebyshev transform. Binomial transform is A083420.
%C Hankel transform is 1, -18, 0, 0, 0, 0, 0, 0, 0, ... - _Philippe Deléham_, Dec 13 2011
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (3).
%F a(n) = 2*3^n - 0^n.
%F a(n) = A025192(n+1), n>0. - _R. J. Mathar_, Sep 02 2008
%F a(n) = Sum_{k=0..n} A093561(n,k)*2^k. - _Philippe Deléham_, Dec 13 2011
%t CoefficientList[Series[(1+3x)/(1-3x),{x,0,30}],x] (* or *) Join[{1}, NestList[3#&,6,30]] (* _Harvey P. Dale_, Nov 08 2011 *)
%o (PARI) Vec((1+3*x)/(1-3*x) + O(x^40)) \\ _Michel Marcus_, Dec 11 2015
%K easy,nonn
%O 0,2
%A _Paul Barry_, Oct 28 2004
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