A173758 Partial sums of A006820.

1, 1, 1, 1, 1, 2, 3, 5, 11, 27, 86, 351, 1895, 12673, 100841, 906332, 8943750, 95165384, 1081035906, 13027523553, 165835586734, 2222527601208, 31273800434817, 460941981112256, 7101107185967292, 114127691657536897, 1910229280483131905, 33244227211086415436

Offset: 0

Author

Jonathan Vos Post, Feb 23 2010

Keywords

• nonn

Comments

Number of connected quartic graphs with at most n nodes.

Crossrefs

Cf. A006820, A033301, A033483.

Connected regular graphs of degree k: A002851 (k=3), A006820 (k=4), A006821 (k=5), A006822 (k=6), A014377 (k=7), A014378 (k=8), A014381 (k=9), A014382 (k=10), A014384 (k=11).

Formula

a(n) = Sum_{k=0..n} A006820(k). [corrected by Georg Fischer, Sep 28 2021]

Extensions

Corrected by Jason Kimberley, Mar 29 2010