A001377 Number of relations with 4 arguments on n nodes.

2, 32896, 402975273205975947935744, 4824670384888174809315457708695329515706856139873561594988392833332671414272

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• nice

References

• W. Oberschelp, "Strukturzahlen in endlichen Relationssystemen", in Contributions to Mathematical Logic (Proceedings 1966 Hanover Colloquium), pp. 199-213, North-Holland Publ., Amsterdam, 1968.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..7
• P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
• W. Oberschelp, Strukturzahlen in endlichen Relationssystemen, in Contributions to Mathematical Logic (Proceedings 1966 Hanover Colloquium), pp. 199-213, North-Holland Publ., Amsterdam, 1968. [Annotated scanned copy]

Crossrefs

Cf. A000595, A000662, A051241.

Programs

Python

from itertools import product
from math import factorial, prod, lcm
from fractions import Fraction
from sympy.utilities.iterables import partitions
def A001377(n): return int(sum(Fraction(1<Chai Wah Wu, Jul 02 2024

Extensions

More terms from Vladeta Jovovic