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 A171872 #6 Apr 28 2016 11:29:36 %S A171872 1,0,1,0,1,1,0,2,3,3,1,1,0,3,17,36,60,56,50,27,19,6,4,1,1,0,6,74,573, %T A171872 2802,10087,26512,55088,91984,130267,157662,168890,158658,133576, %U A171872 98804,65664,38073,19963,9013,3779 %N A171872 Triangle read by columns: Distinct classifications of N elements containing exactly R binary partitions. %C A171872 The bottom of each column is marked by a single 0 in this sequence. Value is 0 for all (N,R) for which N is greater than 2^R. %C A171872 See note on efficient computation in A171871. %H A171872 R. Munafo, <a href="http://mrob.com/pub/math/seq-a005646.html">Classifications of N Elements</a> %Y A171872 First term in each column is A000055(R+1). %Y A171872 Column 4 shares terms with A034189, column 5 with A034190. %K A171872 nonn,tabf %O A171872 0,8 %A A171872 _Robert Munafo_, Jan 21 2010