A342589 T(n,k) is the number of posets of n labeled elements with k covering relations (n>=1, k>=0). Triangle read by rows.

1, 1, 2, 1, 6, 12, 1, 12, 60, 128, 18, 1, 20, 180, 880, 2090, 960, 100, 1, 30, 420, 3480, 17550, 47772, 43920, 15000, 1710, 140, 1, 42, 840, 10360, 84630, 452004, 1428868, 2094960, 1465170, 491540, 90594, 10080, 770

Offset

1,3

Links

Brendan McKay, Table of T(n,k) for n = 1..13

Index entries for sequences related to posets

Example

The triangle starts:
  1: 1
  2: 1 2
  3: 1 6 12
  4: 1 12 60 128 18
  5: 1 20 180 880 2090 960 100
  6: 1 30 420 3480 17550 47772 43920 15000 1710 140
  7: 1 42 840 10360 84630 452004 1428868 2094960 1465170 491540 90594 10080 770

Crossrefs

Cf. A001035 (row sums), A002378 (k=1), A033486 (k=2?), A342447 (unlabeled), A342588 (connected).

Sequence in context: A113025 A113216 A303986 * A325635 A375753 A081064

Adjacent sequences: A342586 A342587 A342588 * A342590 A342591 A342592

Keyword

nonn,tabf,changed

Author

R. J. Mathar, Mar 16 2021

Status

approved