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 A173249 #2 Mar 30 2012 18:40:51 %S A173249 1,2,3,6,22,147,1443,18250,280394,5063363,105063363,2463011054, %T A173249 64380375278,1856540769315,58550453144611,2004745521503986, %U A173249 74062339559431922,2936485391069247715,124376016487663499491 %N A173249 Partial sums of A000272. %C A173249 Partial sums of number of trees on n labeled nodes. The subsequence of primes in this sequence begin: 2, 58550453144611, no more through a(30). %F A173249 a(n) = SUM[i=0..n] A000272(i) = SUM[i=0..n] i^(i-2). %e A173249 a(19) = 1 + 1 + 1 + 3 + 16 + 125 + 1296 + 16807 + 262144 + 4782969 + 100000000 + 2357947691 + 61917364224 + 1792160394037 + 56693912375296 + 1946195068359375 + 72057594037927936 + 2862423051509815793 + 121439531096594251776 + 5480386857784802185939. %Y A173249 Cf. A000055, A000169, A000312, A007778, A007830, A008785-A008791, A033842, A000272, A036361, A036362, A036506, A000055, A054581, A097170 %K A173249 easy,nonn %O A173249 0,2 %A A173249 _Jonathan Vos Post_, Feb 13 2010