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 A099014 #39 Sep 08 2022 08:45:15 %S A099014 0,1,5,20,87,365,1552,6565,27825,117844,499235,2114729,8958240, %T A099014 37947545,160748653,680941780,2884516383,12219006325,51760543280, %U A099014 219261176861,928805254905,3934482189716,16666734024715,70601418270865 %N A099014 a(n) = Fibonacci(n)*(Fibonacci(n-1)^2 + Fibonacci(n+1)^2). %C A099014 Form the matrix A=[1,1,1,1;3,2,1,0;3,1,0,0;1,0,0,0]=(binomial(3-j,i)). Then a(n)=(2,3)-element of A^n. %H A099014 G. C. Greubel, <a href="/A099014/b099014.txt">Table of n, a(n) for n = 0..1000</a> (terms 0..173 from Vincenzo Librandi) %H A099014 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,6,-3,-1). %F A099014 G.f.: x*(1+2*x-x^2)/(1-3*x-6*x^2+3*x^3+x^4) = x*(1+2*x-x^2)/((1+x-x^2)*(1-4*x-x^2)). %F A099014 a(n) = Sum_{k=0..n} (-1)^(k+1)*Fib(k)*(0^(n-k) + 6*A001076(n-k)). %F A099014 a(n) = ((-1)^n*Fib(n) + 3*Fib(3*n))/5. - _Ehren Metcalfe_, May 21 2016 %t A099014 CoefficientList[Series[x*(1 + 2*x - x^2)/(1 - 3*x - 6*x^2 + 3*x^3 + x^4), {x, 0, 50}], x] (* _G. C. Greubel_, Dec 31 2017 *) %t A099014 Join[{0},#[[2]](#[[1]]^2+#[[3]]^2)&/@Partition[Fibonacci[ Range[ 0,30]],3,1]] (* or *) LinearRecurrence[{3,6,-3,-1},{0,1,5,20},30] (* _Harvey P. Dale_, Oct 17 2021 *) %o A099014 (Magma) [Fibonacci(n)*(Fibonacci(n-1)^2+Fibonacci(n+1)^2): n in [0..30]]; // _Vincenzo Librandi_, Jun 05 2011 %o A099014 (PARI) a(n)=fibonacci(n)*(fibonacci(n-1)^2+fibonacci(n+1)^2) \\ _Charles R Greathouse IV_, Jun 05 2011 %Y A099014 Cf. A000045, A056570, A066258, A066259. %K A099014 nonn,easy %O A099014 0,3 %A A099014 _Paul Barry_, Sep 22 2004