A005975 Number of interval graphs on n unlabeled nodes. (Formerly M1224)

1, 2, 4, 10, 27, 92, 369, 1807, 10344, 67659, 491347, 3894446, 33278992, 304256984, 2960093835, 30523315419, 332524557107, 3816805831381, 46048851321131, 582691924941142, 7717878059859874, 106806430860694984, 1541683193805924288, 23173865491070682522

Offset

1,2

References

P. J. Hanlon, personal communication.

R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1980.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

R. W. Robinson, Table of n, a(n) for n = 1..30

Hüseyin Acan, Counting unlabeled interval graphs, arXiv:1810.02040 [math.CO], 2018.

Hüseyin Acan, Sankardeep Chakraborty, Seungbum Jo, Srinivasa Rao Satti, Succinct Data Structures for Families of Interval Graphs, arXiv:1902.09228 [cs.DS], 2019.

Phil Hanlon, Counting interval graphs, Trans. Amer. Math. Soc. 272 (1982), no. 2, 383-426.

S. Hougardy, Classes of perfect graphs, Discr. Math. 306 (2006), 2529-2571.

Yang, Joyce C.; Pippenger, Nicholas On the enumeration of interval graphs Proc. Am. Math. Soc., Ser. B 4, 1-3 (2017).

Crossrefs

Sequence in context: A007776 A268522 A123428 * A048193 A123411 A278418

Adjacent sequences: A005972 A005973 A005974 * A005976 A005977 A005978

Keyword

nonn

Author

N. J. A. Sloane

Extensions

a(21) onwards added by N. J. A. Sloane, Oct 19 2006 from the Robinson reference

Status

approved