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 A023759 #22 Apr 03 2014 17:59:51 %S A023759 0,1,2,3,4,6,7,8,9,12,13,18,21,22,24,25,26,27,36,39,40,54,63,66,67,72, %T A023759 75,76,78,79,80,81,108,117,120,121,162,189,198,201,202,216,225,228, %U A023759 229,234,237,238,240,241,242,243,324,351,360,363,364,486,567,594 %N A023759 Nialpdromes: digits in base 3 are in nonincreasing order. %H A023759 Vincenzo Librandi and Ray Chandler, <a href="/A023759/b023759.txt">Table of n, a(n) for n = 1..1000</a> (first 800 terms from Vincenzo Librandi) %t A023759 Select[Range[0, 4000], Max[Differences[IntegerDigits[#, 3]]] <= 0 &] (* _Vincenzo Librandi_, Dec 26 2012 *) %t A023759 Select[Range[0,600],GreaterEqual@@IntegerDigits[#,3]&] (* _Ray Chandler_, Jan 06 2014 *) %o A023759 (PARI) is(n)=n=digits(n,3); n==vecsort(n,,4) \\ _Charles R Greathouse IV_, Mar 31 2014 %K A023759 nonn,base,easy %O A023759 1,3 %A A023759 _Olivier Gérard_