%I #31 Jun 09 2022 17:56:32

%S 1,1,2,10,98,1960,80176,6686760,1129588960,384610774696,

%T 263104175114712,360908867732030980,991603865814038728388,

%U 5453395569997436383751204,60010050181461052836515513108,1321051495313052133670927704328040,58170762510305449187073353930875222256

%N Number of acyclic digraphs (or DAGs) on n unlabeled vertices with one source and one sink.

%H Andrew Howroyd, <a href="/A345258/b345258.txt">Table of n, a(n) for n = 1..50</a> (terms 1..40 from Mikhail Tikhomirov)

%H Marcel et al., <a href="https://mathoverflow.net/q/395095">Is there a formula for the number of st-dags (DAG with 1 source and 1 sink) with n vertices?</a>, MathOverflow, 2021.

%o (PARI) A345258seq(16) \\ See PARI link in A122078 for program code.

%Y Row sums of A350491.

%Y The labeled version is A165950.

%Y Cf. A003087, A049531, A122078, A350415, A350492.

%K nonn

%O 1,3

%A _Max Alekseyev_, Jun 12 2021

%E a(9) from _Brendan McKay_.

%E Terms a(10) and beyond from _Mikhail Tikhomirov_, Jun 16 2021