A361957 Triangle read by rows: T(n,k) is the number of unlabeled tiered posets with n elements and height k.
1, 0, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 5, 3, 1, 0, 1, 12, 10, 4, 1, 0, 1, 35, 35, 16, 5, 1, 0, 1, 108, 149, 66, 23, 6, 1, 0, 1, 393, 755, 327, 106, 31, 7, 1, 0, 1, 1666, 4736, 1936, 566, 156, 40, 8, 1, 0, 1, 8543, 37394, 14130, 3578, 878, 217, 50, 9, 1
Offset: 0
Examples
Triangle begins: 1; 0, 1; 0, 1, 1; 0, 1, 2, 1; 0, 1, 5, 3, 1; 0, 1, 12, 10, 4, 1; 0, 1, 35, 35, 16, 5, 1; 0, 1, 108, 149, 66, 23, 6, 1; 0, 1, 393, 755, 327, 106, 31, 7, 1; 0, 1, 1666, 4736, 1936, 566, 156, 40, 8, 1; ...
Links
- Andrew Howroyd, Table of n, a(n) for n = 0..860 (rows 0..40).
- Andrew Howroyd, PARI Program, Apr 2023.
Crossrefs
Programs
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PARI
\\ See link for program code. { my(A=A361957tabl(9)); for(i=1, #A, print(A[i, 1..i])) }
Comments