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 A254660 #22 Sep 11 2024 15:07:01
%S A254660 1,7,44,278,1756,11092,70064,442568,2795536,17658352,111541184,
%T A254660 704563808,4450465216,28111918912,177572443904,1121658501248,
%U A254660 7085095895296,44753892374272,282693546036224,1785669060965888,11279401457867776,71247746869138432
%N A254660 Numbers of words on alphabet {0,1,...,6} with no subwords ii, where i is from {0,1,...,4}.
%H A254660 Colin Barker, <a href="/A254660/b254660.txt">Table of n, a(n) for n = 0..1000</a>
%H A254660 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,2).
%F A254660 G.f.: (1 + x)/(1 - 6*x -2*x^2).
%F A254660 a(n) = 6*a(n-1) + 2*a(n-2) with n>1, a(0) = 1, a(1) = 7.
%F A254660 a(n) = ((3-sqrt(11))^n*(-4+sqrt(11)) + (3+sqrt(11))^n*(4+sqrt(11))) / (2*sqrt(11)). - _Colin Barker_, Jan 21 2017
%t A254660 RecurrenceTable[{a[0] == 1, a[1] == 7, a[n] == 6 a[n - 1] + 2 a[n - 2]}, a[n], {n, 0, 20}]
%t A254660 LinearRecurrence[{6,2},{1,7},30] (* _Harvey P. Dale_, Sep 11 2024 *)
%o A254660 (PARI) Vec((1 + x) / (1 - 6*x -2*x^2) + O(x^30)) \\ _Colin Barker_, Jan 21 2017
%Y A254660 Cf. A135030, A126473, A126501, A126528, A254598, A254602.
%K A254660 nonn,easy
%O A254660 0,2
%A A254660 _Milan Janjic_, Feb 04 2015