A112619 Number of connected simple graphs with n vertices, n+2 edges, and vertex degrees no more than 4.

0, 0, 0, 1, 4, 18, 79, 326, 1278, 4875, 17978, 64720, 227842, 787546, 2678207, 8982754, 29761361, 97558039, 316778169, 1019996738, 3259673935, 10347077497, 32644696187, 102425388286, 319754805262

Offset

1,5

Links

Table of n, a(n) for n=1..25.

J. B. Hendrickson and C. A. Parks, Generation and Enumeration of Carbon skeletons, J. Chem. Inf. Comput. Sci., 31 (1991), 101-107. See Table 2, column 3 on page 103.

Michael A. Kappler, GENSMI: Exhaustive Enumeration of Simple Graphs. [gives different a(18)]

Prog

(nauty/bash)
for n in {4..15}; do geng -c -D4 ${n} $((n+2)):$((n+2)) -u; done # Andrey Zabolotskiy, Nov 24 2017

Crossrefs

The analogs for n+k edges with k = -1, 0, ..., 7 are: A000602, A036671, A112410, this sequence, A112408, A112424, A112425, A112426, A112442. Cf. A121941.

Sequence in context: A219137 A240342 A208309 * A196810 A177755 A037965

Adjacent sequences: A112616 A112617 A112618 * A112620 A112621 A112622

Keyword

nonn

Author

Jonathan Vos Post, Dec 21 2005

Extensions

Corrected offset and new name from Andrey Zabolotskiy, Nov 24 2017

a(18) corrected and a(19)-a(25) added by Georg Grasegger, Jun 05 2023

Status

approved