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 A126602 #9 Jan 23 2025 19:44:52
%S A126602 8120,8736,8784,19140,11200,21750,8624,15950,8120,8736,8784,19140,
%T A126602 11200,21750,8624,15950,8120,8736,8784,19140,11200,21750,8624,15950,
%U A126602 8120,8736,8784,19140,11200,21750,8624,15950,8120,8736,8784,19140
%N A126602 a(1)=2^3*5*7*29=8120; for n>1, a(n) = (-1)sigma(a(n-1)).
%C A126602 (-1)sigma is defined in A049060. This is a cyclic sequence whose period is 8, so these numbers are called "(-1)sigma sociable numbers of order 8".
%e A126602 The numbers are 2^3*5*7*29, 2^5*3*7*13, 2^4*3^2*61, 2^2*3*5*11*29, 2^6*5^2*7, 2*3*5^3*29, 2^4*7^2*11, 2*5^2*11*29, then repeat.
%t A126602 LinearRecurrence[{0,0,0,0,0,0,0,1},{8120,8736,8784,19140,11200,21750,8624,15950},50] (* or *) PadRight[{},50,{8120,8736,8784,19140,11200,21750,8624,15950}] (* _Harvey P. Dale_, Jan 23 2025 *)
%K A126602 nonn
%O A126602 1,1
%A A126602 _N. J. A. Sloane_, Feb 14 2008, based on a posting to the Sequence Fans Mailing List by _Yasutoshi Kohmoto_, Feb 02 2005