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 A283679 #24 Jan 30 2021 01:50:40 %S A283679 0,1,3,12,48,197,815,3391,14153,59185,247791,1038186,4351706,18245861, %T A283679 76514483,320899470,1345931153,5645394769,23679726926,99326654214, %U A283679 416638208001,1747652017025,7330817809523,30750407615699,128988186902345,541064919671773,2269598571509748,9520261251293028 %N A283679 G.f.: F(F(F(x))) where F(x) = x/(1-x-x^2) is the g.f. for the Fibonacci numbers. %p A283679 f:= x-> x/(1-x-x^2): %p A283679 a:= n-> coeff(series(f(f(f(x))), x, n+1), x, n): %p A283679 seq(a(n), n=0..23); %K A283679 nonn,easy %O A283679 0,3 %A A283679 _Oboifeng Dira_, Mar 14 2017 %E A283679 Edited by _N. J. A. Sloane_, Apr 21 2017