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 A173383 #6 Sep 14 2021 05:30:42
%S A173383 0,1,2,2,3,4,6,8,12,17,27,41,67,109,187,319,568,1013,1855,3416,6404,
%T A173383 12075,23056,44265,85737,166918,327094,643843,1273776,2529846,5045015,
%U A173383 10094831,20267469,40811048,82413473,166854359,338648851,688887026,1404384063,2868791176,5871429462,12038444069
%N A173383 Partial sums of A000014.
%C A173383 Number of series-reduced trees with <= n nodes.
%F A173383 a(n) = Sum_{k=0..n} A000014(k).
%Y A173383 Cf. A000014, A000055 (trees), A001678 (series-reduced planted trees), A007827 (series-reduced trees by leaves).
%K A173383 easy,nonn
%O A173383 0,3
%A A173383 _Jonathan Vos Post_, Feb 17 2010
%E A173383 a(3)=2 inserted and edited by _Georg Fischer_, Sep 14 2021