A173383 Partial sums of A000014.

0, 1, 2, 2, 3, 4, 6, 8, 12, 17, 27, 41, 67, 109, 187, 319, 568, 1013, 1855, 3416, 6404, 12075, 23056, 44265, 85737, 166918, 327094, 643843, 1273776, 2529846, 5045015, 10094831, 20267469, 40811048, 82413473, 166854359, 338648851, 688887026, 1404384063, 2868791176, 5871429462, 12038444069

Offset: 0

Author

Jonathan Vos Post, Feb 17 2010

Keywords

• easy
• nonn

Comments

Number of series-reduced trees with <= n nodes.

Crossrefs

Cf. A000014, A000055 (trees), A001678 (series-reduced planted trees), A007827 (series-reduced trees by leaves).

Formula

a(n) = Sum_{k=0..n} A000014(k).

Extensions

a(3)=2 inserted and edited by Georg Fischer, Sep 14 2021