A256411 Triangle read by rows: T(n,k) (1 <= k <= n) = number of ascendingly generated semigroups of order n with k generators.

1, 2, 8, 3, 37, 113, 4, 145, 1257, 3492, 5, 452, 9020, 67394, 183732, 6, 1374, 60826, 938194, 6398792, 17061118, 7, 3933, 356023, 30492722, 466578957, 3032145644, 7743056064

Offset

1,2

Links

Table of n, a(n) for n=1..28.

Alex Bailey, Martin Finn-Sell, Robert Snocken, Subsemigroup, ideal and congruence growth of free semigroups, arXiv preprint arXiv:1409.2444 [math.GR], 2014.

Example

Triangle begins:
  1;
  2,    8;
  3,   37,    113;
  4,  145,   1257,     3492;
  5,  452,   9020,    67394,    183732;
  6, 1374,  60826,   938194,   6398792,   17061118;
  7, 3933, 356023, 30492722, 466578957, 3032145644, 7743056064;
  ...

Crossrefs

Main diagonal is A023814. Column 2 is A256412.

Sequence in context: A292930 A126951 A282637 * A218609 A268491 A076588

Adjacent sequences: A256408 A256409 A256410 * A256412 A256413 A256414

Keyword

nonn,tabl,more

Author

N. J. A. Sloane, Apr 03 2015

Status

approved