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 A174566 #2 Mar 30 2012 18:40:51 %S A174566 1,2,4,7,13,23,43,80,156,308,628,1300,2754,5908,12867,28306,62914, %T A174566 140902,317887,721397,1646080,3773415,8686867,20072822,46541053, %U A174566 108241285,252447554,590284775,1383498325,3249679480,7648547152 %N A174566 Partial sums of A003214. %C A174566 Partial sums of number of binary forests with n nodes. The subsequence of primes in this partial sum begins: 2, 7, 13, 23, 43, 317887, 721397, 238855831229, 154308201825571245947273 = a(65). %F A174566 a(n) = SUM[i=0..n] A003214(i). %e A174566 a(34) = 1 + 1 + 2 + 3 + 6 + 10 + 20 + 37 + 76 + 152 + 320 + 672 + 1454 + 3154 + 6959 + 15439 + 34608 + 77988 + 176985 + 403510 + 924683 + 2127335 + 4913452 + 11385955 + 26468231 + 61700232 + 144206269 + 337837221 + 793213550 + 1866181155 + 4398867672 + 10387045476 + 24567374217 + 58196129468 + 138056734916 = 238855831229 is prime, %Y A174566 Cf. A003214. %K A174566 easy,nonn %O A174566 0,2 %A A174566 _Jonathan Vos Post_, Mar 22 2010