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 A081656 #23 May 06 2024 14:33:21
%S A081656 1,10,68,424,2576,15520,93248,559744,3358976,20154880,120931328,
%T A081656 725592064,4353560576,26121379840,156728311808,940369936384,
%U A081656 5642219749376,33853318758400,203119913074688,1218719479496704,7312316879077376,43873901278658560,263243407680339968
%N A081656 a(n) = 2*6^n - 2^n.
%C A081656 Binomial transform of A081655.
%C A081656 Inverse binomial transform of A081657.
%H A081656 Vincenzo Librandi, <a href="/A081656/b081656.txt">Table of n, a(n) for n = 0..1000</a>
%H A081656 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-12).
%F A081656 G.f.: (1+2*x)/((1-6*x)(1-2*x)).
%F A081656 E.g.f.: 2*exp(6*x) - exp(2*x).
%F A081656 a(0)=1, a(2)=10; for n>2, a(n) = 8*a(n-1) - 12*a(n-2). - _Vincenzo Librandi_, Aug 10 2013
%t A081656 CoefficientList[Series[(1 + 2 x) / ((1 - 6 x) (1 - 2 x)), {x, 0, 40}], x] (* _Vincenzo Librandi_, Aug 10 2013 *)
%t A081656 Table[2*6^n-2^n,{n,0,20}] (* or *) LinearRecurrence[{8,-12},{1,10},20] (* _Harvey P. Dale_, Mar 17 2019 *)
%o A081656 (Magma) [2*6^n-2^n: n in [0..30]]; // _Vincenzo Librandi_, Aug 10 2013
%o A081656 (PARI) a(n)=2*6^n-2^n \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A081656 Third column of array A094424.
%Y A081656 Cf. A081655, A081657.
%K A081656 easy,nonn
%O A081656 0,2
%A A081656 _Paul Barry_, Mar 26 2003