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

1,2

Comments

See A339297 for additional details.

Links

Table of n, a(n) for n=1..18.

Prog

(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)) )}

Crossrefs

Row sums of A339297.

Cf. A339229.

Sequence in context: A357337 A227020 A119293 * A366315 A328269 A136046

Adjacent sequences: A339295 A339296 A339297 * A339299 A339300 A339301

Keyword

nonn

Author

Andrew Howroyd, Dec 22 2020

Status

approved