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 A289415 #9 Jul 06 2017 10:30:38 %S A289415 1,11,132,1694,22748,314116,4408272,62429224,888533008,12680511536, %T A289415 181232622912,2592261435104,37094163051968,530922829281856, %U A289415 7599944308484352,108797263565651584,1557545924511056128,22298311347021560576,319232797938258158592 %N A289415 a(n) = ((11-sqrt(11))^n + (11+sqrt(11))^n) / 2. %H A289415 Colin Barker, <a href="/A289415/b289415.txt">Table of n, a(n) for n = 0..850</a> %H A289415 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (22,-110). %F A289415 G.f.: (1 - 11*x) / (1 - 22*x + 110*x^2). %F A289415 a(n) = 22*a(n-1) - 110*a(n-2) for n>1. %p A289415 a:= n-> (<<0|1>, <-110|22>>^n. <<1,11>>)[1,1]: %p A289415 seq(a(n), n=0..25); # _Alois P. Heinz_, Jul 06 2017 %o A289415 (PARI) Vec((1 - 11*x) / (1 - 22*x + 110*x^2) + O(x^25)) %Y A289415 Cf. A083881, A090139, A143079, A145301, A145302, A145303, A289414. %K A289415 nonn,easy %O A289415 0,2 %A A289415 _Colin Barker_, Jul 06 2017