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 A089756 #16 May 10 2020 14:27:45 %S A089756 1,10,19,28,37,2,11,20,29,38,3,12,21,30,39,4,13,22,31,40,5,14,23,32, %T A089756 41,6,15,24,33,42,7,16,25,34,43,8,17,26,35,44,9,18,27,36,1,10,19,28, %U A089756 37,2,11,20,29,38,3,12,21,30,39,4,13,22,31,40,5,14,23,32,41,6,15,24,33,42,7,16,25,34,43,8,17 %N A089756 a(1)=1 and a(i+1)=a(i)+9 if a(i)<=35, and a(i+1)=a(i)-35 if a(i)>35. %C A089756 Infinite cyclic sequence with a(44*j+k)=a(k) and 0 < k < 45 with all and only one time the 44th first integers > 0. %C A089756 Periodic with period = 44. - _Harvey P. Dale_, Nov 04 2019 %H A089756 <a href="/index/Rec#order_44">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1). %p A089756 A089756 := proc(n) %p A089756 option remember; %p A089756 if n = 1 then %p A089756 1; %p A089756 else %p A089756 if procname(n-1) > 35 then %p A089756 procname(n-1)-35 ; %p A089756 else %p A089756 procname(n-1)+9 ; %p A089756 end if; %p A089756 end if; %p A089756 end proc: %p A089756 seq(A089756(n),n=1..100) ; # _R. J. Mathar_, Feb 28 2019 %t A089756 NestList[If[#<36,#+9,#-35]&,1,80] (* _Harvey P. Dale_, Nov 04 2019 *) %K A089756 nonn,easy,less %O A089756 1,2 %A A089756 _Pierre CAMI_, Jan 08 2004