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 A151889 #16 Apr 06 2025 14:58:44
%S A151889 2,3,8,13,34,55,144,233,610,987,2584,4181,10946,17711,46368,75025,
%T A151889 196418,317811,832040,1346269,3524578,5702887,14930352,24157817,
%U A151889 63245986,102334155,267914296,433494437,1134903170,1836311903
%N A151889 a(1)=2, a(2)=3; a(2k-1)=2a(2k-2)+a(2k-3), a(2k)=3a(2k-2)+2a(2k-3), k >= 2.
%C A151889 Because of G.f. in Formula section, numbers k + 1 such that A054347(k)/k is an integer. - _Ctibor O. Zizka_, Apr 02 2025
%H A151889 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,4,0,1).
%F A151889 a(2k-1) = Fib(3k-1), a(2k) = Fib(3k).
%F A151889 G.f.: -(x^3+3*x+2)*x/(x^4+4*x^2-1). - _Alois P. Heinz_, Jun 20 2013
%t A151889 LinearRecurrence[{0,4,0,1},{2,3,8,13},30] (* _Harvey P. Dale_, Dec 31 2021 *)
%o A151889 (PARI) a(n) = if (n==1, 2, if (n==2, 3, if (n%2, 2*a(n-1)+a(n-2), 3*a(n-2)+2*a(n-3)))) \\ _Michel Marcus_, Jun 20 2013
%Y A151889 Cf. A000045, A000201, A054347.
%K A151889 nonn,easy
%O A151889 1,1
%A A151889 Antonia Redondo Buitrago (aredondo(AT)sabuco.com), Jul 23 2009