A173249 Partial sums of A000272.

1, 2, 3, 6, 22, 147, 1443, 18250, 280394, 5063363, 105063363, 2463011054, 64380375278, 1856540769315, 58550453144611, 2004745521503986, 74062339559431922, 2936485391069247715, 124376016487663499491

Offset

0,2

Comments

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).

Links

Table of n, a(n) for n=0..18.

Formula

a(n) = SUM[i=0..n] A000272(i) = SUM[i=0..n] i^(i-2).

Example

a(19) = 1 + 1 + 1 + 3 + 16 + 125 + 1296 + 16807 + 262144 + 4782969 + 100000000 + 2357947691 + 61917364224 + 1792160394037 + 56693912375296 + 1946195068359375 + 72057594037927936 + 2862423051509815793 + 121439531096594251776 + 5480386857784802185939.

Crossrefs

Cf. A000055, A000169, A000312, A007778, A007830, A008785-A008791, A033842, A000272, A036361, A036362, A036506, A000055, A054581, A097170

Sequence in context: A015764 A015759 A260562 * A303584 A261014 A000616

Adjacent sequences: A173246 A173247 A173248 * A173250 A173251 A173252

Keyword

easy,nonn

Author

Jonathan Vos Post, Feb 13 2010

Status

approved