A101620 Decimal encoding of digraph topologies.

1, 3, 9, 11, 13, 15, 129, 131, 133, 137, 139, 141, 143, 145, 153, 161, 163, 165, 171, 175, 177, 179, 187, 193, 195, 197, 205, 207, 209, 213, 221, 241, 243, 245, 255

Offset

1,2

Comments

The sequence encodes labeled digraph topologies as described by and counted in A000798.

Links

Table of n, a(n) for n=1..35.

Example

Let a = 2, b = 4, c = 16, d = 256, ...
a(19) = 171 because we can map { }, a, ab, ac, abc to 1 + 2 + 8 + 32 + 128
Viewed as an array the table begins
1
3
9 11 13 15
129 131 133 137 139 141 143 145 153 161 163 165 171 175 177 ...
with respectively 1 1 4 29 355 ... (A000798) entries on each row.

Crossrefs

Cf. A000798, A001035, A001930, A074486.

Sequence in context: A074261 A059868 A101735 * A376509 A235583 A287333

Adjacent sequences: A101617 A101618 A101619 * A101621 A101622 A101623

Keyword

more,nonn,tabf,base

Author

Alford Arnold, Dec 10 2004

Status

approved