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 A338024 #26 Oct 27 2020 00:28:05 %S A338024 1,6,15,28,57,98,179,304,521,894,1519,2576,4381,7434,12603,21380, %T A338024 36265,61486,104263,176808,299797 %N A338024 Minimal number of moves for the cyclic variant of Hanoi's tower for 4 pegs and n disks, with the final peg one step away. %H A338024 Martin Ehrenstein, <a href="/A338024/a338024.txt">(C++) Program</a> %F A338024 Conjecture: a(n) = a(n-1) + a(n-2) + a(n-3) - 2*a(n-5) for n > 11. %F A338024 Conjectured g.f.: x*(1+5*x+8*x^2+6*x^3+8*x^4+8*x^6-4*x^8+4*x^9-4*x^10)/((1-x)*(1+x)*(1-x-2*x^3)). - _Stefano Spezia_, Oct 07 2020 after _Paul Zimmermann_ %e A338024 For n=2, assume the two disks are on North initially, first move the smallest one to West in 3 moves, then the largest one to East in 1 move, and the smallest one to East also in 2 moves, with a total of 6 moves. Each disk has a number of moves which is 1 mod 4, thus a(n) = n mod 4. %o A338024 (C++) See Martin Ehrenstein link, Oct 27 2020 %Y A338024 Cf. A292764, A338089. %K A338024 nonn,more %O A338024 1,2 %A A338024 _Paul Zimmermann_, Oct 07 2020 %E A338024 a(17)-a(21) from _Martin Ehrenstein_, Oct 25 2020