A023646 Number of vertex-transitive graphs of valency 3 with 2n nodes.

1, 2, 3, 3, 7, 3, 7, 7, 11, 3, 20, 5, 10, 15, 17, 5, 24, 5, 25, 15, 11, 5, 56, 12, 16, 20, 28, 7, 65, 7, 43, 16, 18, 17, 74, 9, 17, 21, 62, 9, 56, 9, 30, 41, 19, 9, 156, 16, 45, 23, 40, 11, 79, 25, 70, 25, 26, 11, 195, 13, 25, 46, 126, 27, 63, 13, 48, 26, 66

Offset

2,2

References

CRC Handbook of Combinatorial Designs, 1996, p. 649.

Links

Andrew Howroyd, Table of n, a(n) for n = 2..640

Formula

a(n) = Sum_{d|n} A032355(d). - Andrew Howroyd, Nov 07 2025

Crossrefs

Even-indexed terms of column k=3 of A319367.

Sequence in context: A234943 A209494 A082910 * A056225 A343390 A105437

Adjacent sequences: A023643 A023644 A023645 * A023647 A023648 A023649

Keyword

nonn

Author

N. J. A. Sloane

Extensions

a(14)-a(15) added by Andrew Howroyd, Sep 18 2018

a(16) onward added using A032355 by Andrew Howroyd, Nov 07 2025

Status

approved