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A126757 Number of n-node connected graphs with no cycles of length less than 5. 4
1, 1, 1, 2, 4, 8, 18, 47, 137, 464, 1793, 8167, 43645, 275480, 2045279, 17772647, 179593823, 2098423758, 28215583324, 434936005284, 7662164738118 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..21.

Keith M. Briggs, Combinatorial Graph Theory

CombOS - Combinatorial Object Server, Generate graphs

FORMULA

This is the inverse Euler transform of A006787. - Conjectured by Vladeta Jovovic, Jun 16 2008, proved by Max Alekseyev and Brendan McKay, Jun 17 2008

MATHEMATICA

A006787 = Cases[Import["https://oeis.org/A006787/b006787.txt", "Table"], {_, _}][[All, 2]];

(* EulerInvTransform is defined in A022562 *)

EulerInvTransform[A006787] (* Jean-Fran├žois Alcover, May 13 2019, updated Mar 17 2020 *)

CROSSREFS

Cf. A006787, A140440.

Sequence in context: A252653 A006771 A113989 * A034766 A099785 A333497

Adjacent sequences:  A126754 A126755 A126756 * A126758 A126759 A126760

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Feb 18 2007

EXTENSIONS

Definition corrected by Max Alekseyev and Brendan McKay, Jun 17 2008

a(20)-a(21) using Brendan McKay's extension to A006787 by Alois P. Heinz, Mar 11 2018

STATUS

approved

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Last modified August 11 15:10 EDT 2022. Contains 356066 sequences. (Running on oeis4.)