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 A143488 #22 Mar 01 2024 10:30:27 %S A143488 1,1,1,2,2,1,1,1,2,2,3,3,4,4,4,3,3,4,4,4,3,3,2,2,1,1,1,2,2,1,1,1,2,2, %T A143488 3,3,4,4,4,3,3,4,4,4,3,3,2,2,1,1,1,2,2,1,1,1,2,2,3,3,4,4,4,3,3,4,4,4, %U A143488 3,3,2,2,1,1,1,2,2,1,1,1,2,2,3,3,4,4,4,3,3,4,4,4,3,3,2,2,1,1,1,2,2,1,1,1,2 %N A143488 "Fourth down, Extream [sic] between the two farthest Bells from it" in bell-ringing is a sequence of permutations p_1=(1,2,3,4), p_2=(1,2,4,3), .. which runs through all permutations of {1,2,3,4} with period 24; sequence gives position of bell 1 (the treble bell) in n-th permutation. %C A143488 Start with (1,2,3,4), i.e. the first permutation of {1,2,3} followed by 4; then for each next permutation, transpose 4 one to the left; if at position 1, replace {1,2,3} recursively by the next permutation of these numbers. Thereafter, for each next permutation, transpose 4 to the right. And so on. %H A143488 Richard Duckworth and Fabian Stedman, <a href="http://www.gutenberg.org/files/18567/18567-h/18567-h.htm">Tintinnalogia, or, the Art of Ringing</a>, (1671). Released by Project Gutenberg, 2006. %H A143488 <a href="/index/Be#bell_ringing">Index entries for sequences related to bell ringing</a> %H A143488 <a href="/index/Rec#order_13">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,0,0,0,-1,1). %F A143488 Period 24. %F A143488 From _Chai Wah Wu_, Jan 15 2020: (Start) %F A143488 a(n) = a(n-1) - a(n-12) + a(n-13) for n > 13. %F A143488 G.f.: x*(-2*x^12 - x^10 - x^8 + x^5 - x^3 - 1)/(x^13 - x^12 + x - 1). (End) %e A143488 The full list of the 24 permutations is as follows (the present sequence gives position of bell 1): %e A143488 1 2 3 4 %e A143488 1 2 4 3 %e A143488 1 4 2 3 %e A143488 4 1 2 3 %e A143488 4 1 3 2 %e A143488 1 4 3 2 %e A143488 1 3 4 2 %e A143488 1 3 2 4 %e A143488 3 1 2 4 %e A143488 3 1 4 2 %e A143488 3 4 1 2 %e A143488 4 3 1 2 %e A143488 4 3 2 1 %e A143488 3 4 2 1 %e A143488 3 2 4 1 %e A143488 3 2 1 4 %e A143488 2 3 1 4 %e A143488 2 3 4 1 %e A143488 2 4 3 1 %e A143488 4 2 3 1 %e A143488 4 2 1 3 %e A143488 2 4 1 3 %e A143488 2 1 4 3 %e A143488 2 1 3 4 %p A143488 ring:= proc(k::nonnegint) local p,i,left,l,nf, ini; if k<=1 then proc() [1$k] end else ini:= proc() p:= ring(k-1); i:= k; left:= true; l:= p(); nf:= k! end; ini(); proc() local ll; ll:= [seq(l[t], t=1..(i-1)), k, seq(l[t], t=i..(k-1))]; if left then if i>1 then i:= i-1 else left:= false; l:=p() fi else if i<k then i:= i+1 else left:= true; l:=p() fi fi; nf:= nf-1; if nf = 0 then ini() fi; ll end fi end: bell := proc(k) option remember; local p; p:= ring(k); [seq(p(), i=1..k!)] end: indx:= proc(l, k) local i; for i from 1 to nops(l) do if l[i]=k then break fi od; i end: a:= n-> indx(bell(4)[modp(n-1,24)+1], 1): seq(a(n), n=1..121); %t A143488 LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1}, {1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 3, 3, 4, 4, 4, 3}, 105] (* _Jean-François Alcover_, Mar 15 2021 *) %Y A143488 Cf. A143484, A143485, A143486, A143487, A143489, A143490, A090281. %K A143488 nonn,easy %O A143488 1,4 %A A143488 _Alois P. Heinz_, Aug 19 2008