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 A166450 #11 Sep 08 2022 08:45:48 %S A166450 1,6,3,18,9,54,27,162,81,486,243,1458,729,4374,2187,13122,6561,39366, %T A166450 19683,118098,59049,354294,177147,1062882,531441,3188646,1594323, %U A166450 9565938,4782969,28697814,14348907,86093442,43046721,258280326 %N A166450 a(n) = 3*a(n-2) for n > 2; a(1) = 1, a(2) = 6. %C A166450 Interleaving of A000244 and 6*A000244. %C A166450 Second binomial transform is A055845. Sixth binomial transform is A153597. %H A166450 Vincenzo Librandi, <a href="/A166450/b166450.txt">Table of n, a(n) for n = 1..1000</a> %H A166450 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,3). %F A166450 a(n) = (3+(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2. %F A166450 G.f.: x*(1+6*x)/(1-3*x^2). %t A166450 LinearRecurrence[{0,3},{1,6}, 50] (* _G. C. Greubel_, May 14 2016 *) %o A166450 (Magma) [ n le 2 select 5*n-4 else 3*Self(n-2): n in [1..35] ]; %Y A166450 Cf. A000244 (powers of 3), A055845, A153597. %K A166450 nonn,easy %O A166450 1,2 %A A166450 _Klaus Brockhaus_, Oct 13 2009