A055127 Triangle T(n,k) of numbers of proper k-covers of an unlabeled n-set, k=1..2^n-2.

0, 1, 0, 2, 5, 4, 2, 1, 0, 4, 19, 58, 113, 168, 193, 171, 119, 68, 29, 10, 3, 1, 0, 6, 53, 325, 1551, 6007, 19533, 54119, 128936, 266085, 478223, 751487, 1035609, 1254303, 1336855, 1254307, 1035622, 751526, 478320, 266272, 129226, 54484, 19898, 6297

Offset

2,4

Links

Table of n, a(n) for n=2..47.

Eric Weisstein's World of Mathematics, Proper covers

Example

[0, 1], [0, 2, 5, 4, 2, 1], [0, 4, 19, 58, 113, 168, 193, 171, 119, 68, 29, 10, 3, 1], ...; There are 113 proper 5-covers of an unlabeled 4-set.

Crossrefs

Cf. A052265, A055080, A007537. Row sums give A055152.

Sequence in context: A009738 A268647 A177067 * A152669 A324051 A307037

Adjacent sequences: A055124 A055125 A055126 * A055128 A055129 A055130

Keyword

nonn,tabf

Author

Vladeta Jovovic, Jun 14 2000

Status

approved