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 A058545 #4 Mar 30 2012 16:48:56 %S A058545 23,45,57,91,161,291,481,911,1821,3031,5621,9759,16261,29199,48661, %T A058545 97321,180731,361461,595359,914661,1302543,1810989,2732295,3594645, %U A058545 4393215,5513805,5482215,6700245,8913663,12588669,19116087,31171125 %N A058545 Trajectory of 23 under map that sends x to 3x - sigma(x), where sigma(x) is the sum of the divisors of x. %Y A058545 Cf. A037159, A058541, A058542. %K A058545 nonn %O A058545 0,1 %A A058545 _N. J. A. Sloane_, Dec 24 2000