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 A162304 #9 Mar 11 2014 20:27:43 %S A162304 105,120,136,153,190,210,231,253,276,325,351,378,406,435,465,496,528, %T A162304 561,630,703,741,780,820,861,903,946,1081,1128,1176,1225,1431,1770, %U A162304 1891,2080,2278,2556,2628,2775,2926,3321,3403,3655,3828,4005,4465,4656,5253 %N A162304 Triangular numbers that contain exactly 3 different decimal digits. %t A162304 Select[Accumulate[Range[150]],Count[DigitCount[#],0]==7&] (* _Harvey P. Dale_, Dec 02 2010 *) %o A162304 (PARI) isA162304(n)=issquare(n<<3+1)&#vecsort(Vec(Str(n)),,8)==3 %K A162304 nonn,base %O A162304 1,1 %A A162304 _Claudio Meller_, Jun 30 2009