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 A335690 #15 Feb 20 2023 17:32:37 %S A335690 1,2,2,5,4,5,2,2,1,2,2,5,4,5,2,2,1,2,2,5,4,5,2,2,1,2,2,5,4,5,2,2,1,2, %T A335690 2,5,4,5,2,2,1,2,2,5,4,5,2,2,1,2,2,5,4,5,2,2,1,2,2,5,4,5,2,2,1,2,2,5, %U A335690 4,5,2,2,1,2,2,5,4,5,2,2,1,2,2,5,4 %N A335690 a(1) = 1, a(2) = a(3) = 2; a(n) = (a(n-1) + a(n-2) + 1)/a(n-3) (for n>3). %C A335690 This is another illustration of the 8-cycle discovered by H. Todd - see Lyness, Note 1847. Compare A076844. - _N. J. A. Sloane_, Jul 19 2020 %H A335690 R. C. Lyness, <a href="https://www.jstor.org/stable/3606036">Note 1581. Cycles</a>, Math. Gazette, 26 (1942), 62. %H A335690 R. C. Lyness, <a href="https://www.jstor.org/stable/3609268">Note 1847. Cycles</a>, Math. Gaz., 29 (1945), 231-233. %H A335690 R. C. Lyness, <a href="https://www.jstor.org/stable/3612778">Note 2952. Cycles</a>, Math. Gaz., 45 (1961), 207-209. %p A335690 a := 1; b := 1; c := 1; f := proc(n) option remember; global a,b,c; if n=1 then RETURN(a); fi; if n=2 then RETURN(b); fi; if n=3 then RETURN(c); fi; RETURN((f(n-1)+f(n-2)+1)/f(n-3)); end; %t A335690 RecurrenceTable[{a[1]==1,a[2]==a[3]==2,a[n]==(a[n-1]+a[n-2]+1)/a[n-3]},a,{n,90}] (* or *) PadRight[{},90,{1,2,2,5,4,5,2,2}] (* _Harvey P. Dale_, May 28 2021 *) %Y A335690 Cf. A076839, A076844. %K A335690 nonn %O A335690 1,2 %A A335690 _N. J. A. Sloane_, Jul 19 2020