OFFSET
1,1
COMMENTS
Partial sums of number of free binary rooted trees of height n. The subsequence of primes in this partial sum begins: 2, 61, no more through a(12).
FORMULA
a(n) = Sum_{i=1..n} A005588(i).
EXAMPLE
a(9) = 2 + 7 + 52 + 2133 + 2590407 + 3374951541062 + 5695183504479116640376509 + 16217557574922386301420514191523784895639577710480 + 131504586847961235687181874578063117114329409897550318273792033024340388219235081096658023517076950.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Feb 19 2010
STATUS
approved