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 A085309 #9 Apr 13 2022 20:22:33
%S A085309 213,323,639,713
%N A085309 Initial values providing nontrivial cyclic attractor when function defined in A085307 is iterated.
%F A085309 Algorithm: 1# factorize n; 2# arrange prime-factors by decreasing size; 3# concatenate prime factors and interpret the result as decimal number.Iterate 1#, 2#, 3#.
%e A085309 n=213 gives {213,713,3123,3473,15123,713},
%e A085309 n=323 gives {323,1917,713,3123,3473,15123,713},
%e A085309 n=639 gives {639,713,3123,3473,15123,713}.
%Y A085309 Cf. A084317-A084319, A085307, A085308, A085309.
%K A085309 base,nonn
%O A085309 1,1
%A A085309 _Labos Elemer_, Jun 27 2003