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URL: https://oeis.org/A361912

⇱ A361912 - OEIS

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A361912
The number of unlabeled graded posets with n elements.
5
1, 1, 2, 4, 10, 28, 93, 354, 1621, 9110, 64801, 595976, 7204091, 115561423, 2473540433, 70853213144, 2720354016419, 140170631441858, 9702605436760235, 903309202327818566, 113234129823368903523, 19137461395401601912043, 4366007821745938984134203
OFFSET
0,3
COMMENTS
A partially ordered set is graded if all maximal chains have the same length. This is called tiered by some authors.
LINKS
PROG
(SageMath) sum(1 for P in posets(n) if P.is_graded())
(PARI) \\ See PARI link in A361957 for program code.
A361912seq(20) \\ Andrew Howroyd, Apr 03 2023
CROSSREFS
Row sums of A361957.
Cf. A000112, A223911 (labeled), A001833, A361920, A361959 (connected).
Sequence in context: A271207 A091175 A090594 * A188496 A369079 A191501
KEYWORD
nonn
AUTHOR
Martin Rubey, Mar 29 2023
EXTENSIONS
Terms a(8) and beyond from Andrew Howroyd, Mar 30 2023
STATUS
approved