A339298 Number of oriented series-parallel networks with n integer valued elements spanning an initial interval of positive integers and without multiple unit elements in parallel.

1, 3, 26, 339, 6241, 146261, 4192048, 141800728, 5532432894, 244530744314, 12076710992326, 659091388208810, 39390323152318533, 2558571976136883890, 179469998189344217166, 13520418589045722826274, 1088748555389998857776521, 93324804498600668393385498

Offset: 1

Author

Andrew Howroyd, Dec 22 2020

Keywords

• nonn

Comments

See A339297 for additional details.

Crossrefs

Row sums of A339297.

Cf. A339229.

Programs

PARI

\\ See A339297 for R(n, k).
seq(n)={sum(k=1, n, R(n, k)*sum(r=k, n, binomial(r, k)*(-1)^(r-k)) )}