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 A259989 #17 Jul 27 2015 17:20:49 %S A259989 4,44,344,5344,5344,205344,4205344,34205344,334205344,3334205344, %T A259989 3334205344,403334205344,403334205344,403334205344,400403334205344, %U A259989 1400403334205344,41400403334205344,241400403334205344,4241400403334205344,34241400403334205344 %N A259989 This sequence and A259988 are base-6 analogs of A007185 and A016090, written in base 6. %C A259989 See Schut (1991) for precise definition. %C A259989 Ignoring repetitions, the subsequence of A201821 of terms ending in 4. - _Eric M. Schmidt_, Jul 18 2015 %D A259989 C. P. Schut, Idempotents. Report AM-R9101, Centrum voor Wiskunde en Informatica, Amsterdam, 1991. %H A259989 Eric M. Schmidt, <a href="/A259989/b259989.txt">Table of n, a(n) for n = 1..1000</a> %o A259989 (Sage) def a(n) : return Integer(crt(0, 1, 2^n, 3^n).str(6)) # _Eric M. Schmidt_, Jul 18 2015 %Y A259989 Cf. A007185, A016090, A201821, A237583, A259986-A259991. %K A259989 nonn,base %O A259989 1,1 %A A259989 _N. J. A. Sloane_, Jul 13 2015 %E A259989 Corrected and extended by _Eric M. Schmidt_, Jul 18 2015