|
%I #8 Nov 07 2019 19:24:37
%S 1,5,132,22662,29174514,286151774704,21712410740238954,
%T 12980058344488389640470,62082372574276838787463958455,
%U 2405193558246444686967534052419452898,762399004073792344564641131264446658930745417
%N Number of connected directed 2-multigraphs on n nodes.
%C A 2-multigraph is similar to an ordinary graph except there are 0, 1 or 2 edges between any two nodes (self-loops are not allowed).
%H Andrew Howroyd, <a href="/A053517/b053517.txt">Table of n, a(n) for n = 1..40</a>
%F Inverse Euler transform of A053467.
%Y Cf. A053467.
%K easy,nonn
%O 1,2
%A _Vladeta Jovovic_, Jan 14 2000
%E a(11) from _Andrew Howroyd_, Nov 07 2019
| 