A007122 Number of unlabeled identity connected unit interval graphs with n nodes. (Formerly M1288)

0, 0, 0, 0, 0, 2, 4, 15, 36, 108, 276, 770, 2036, 5586, 15072, 41370, 113184, 312488, 863824, 2401344, 6692368, 18724990, 52531788, 147824963, 417006316, 1179285900, 3342274092, 9492427854, 27011049612, 76999988534

Offset

1,6

References

R. W. Robinson, 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..190

Crossrefs

Cf. A005219.

Sequence in context: A196260 A073814 A181442 * A005219 A153945 A153942

Adjacent sequences: A007119 A007120 A007121 * A007123 A007124 A007125

Keyword

nonn,nice

Author

N. J. A. Sloane

Status

approved