A394732 Number of transitive relations on an n-set with at most five ordered pairs.

1, 2, 13, 152, 1700, 13932, 85830, 420638, 1716899, 6040894, 18802523, 52809868, 135947198, 324787256, 727441548, 1540202274, 3104066741, 5989089818, 11116712473, 19932794912, 34647071560, 58558172324, 96487250498, 155347652550, 244882989111, 378611450006, 575020279367, 859061019988, 1264003479362

Offset

0,2

Links

Table of n, a(n) for n=0..28.

Formula

a(n) = 1 + A000290(n) + A349919(n) + A349927(n) + A349849(n) + A348634(n).

Example

a(2) = 13 because all 13 transitive relations on a 2-set have at most 5 (actually less than 5) ordered pairs.

Crossrefs

Cf. A000290, A349919, A349927, A349849, A348634.

Sequence in context: A058192 A380717 A379456 * A367820 A377831 A054382

Adjacent sequences: A394729 A394730 A394731 * A394733 A394734 A394735

Keyword

nonn,easy

Author

Firdous Ahmad Mala, Mar 30 2026

Status

approved