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 A107904 #27 Dec 06 2024 07:00:51
%S A107904 1,6,12,72,144,864,1728,10368,20736,124416,248832,1492992,2985984,
%T A107904 17915904,35831808,214990848,429981696,2579890176,5159780352,
%U A107904 30958682112,61917364224,371504185344,743008370688,4458050224128,8916100448256,53496602689536,106993205379072
%N A107904 Expansion of (1+6x)/(1-12x^2).
%C A107904 Fourth binomial transform is A107903.
%H A107904 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,12).
%F A107904 a(n) = ((1+sqrt(3))*(2*sqrt(3))^n + (1-sqrt(3))*(-2*sqrt(3))^n)/2.
%F A107904 a(2n) = 12^n, a(2n+1) = 6*12^n.
%F A107904 a(n) = 2^n*A108411(n+1). - _R. J. Mathar_, Aug 15 2023
%F A107904 From _Amiram Eldar_, Dec 06 2024: (Start)
%F A107904 Sum_{n>=0} 1/a(n) = 14/11.
%F A107904 Sum_{n>=0} (-1)^n/a(n) = 10/11. (End)
%t A107904 LinearRecurrence[{0,12},{1,6},30] (* _Harvey P. Dale_, Sep 22 2014 *)
%Y A107904 Cf. A094015, A107903, A108411.
%K A107904 easy,nonn
%O A107904 0,2
%A A107904 _Paul Barry_, May 27 2005