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A281003 a(n) is the number of unlabeled simple graphs with n vertices that have no automorphisms of odd parity. 0
1, 0, 0, 1, 6, 28, 252, 4726, 150324, 8308928, 817860888, 144938364368, 46784208920560, 27789645300385184, 30630702203393521120, 63070163901389334212336, 243902725979609232729020320, 1779250465648201682685291759744 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..18.

Brendan McKay, Isoclasses of simple graphs

MATHEMATICA

(* This assumes you have Brendan McKay's files listing isoclasses of simple graphs (see link), and starts from a(2), as there is no graph1.g6 *)

Table[

Length@ Select[

   Import["graph" <> ToString[i] <> ".g6"],

   Function[g,

    ! AnyTrue[GroupElements[GraphAutomorphismGroup[g]],

      Apply[Times, (-1)^(Length /@ First[#] - 1)] == -1 &]

    ]

   ],

{i, 2, 9}

]

CROSSREFS

Sequence in context: A216413 A090898 A134872 * A049603 A333927 A035527

Adjacent sequences:  A281000 A281001 A281002 * A281004 A281005 A281006

KEYWORD

nonn

AUTHOR

Mariano Suárez-Álvarez, Jan 12 2017

EXTENSIONS

More terms from Ira M. Gessel, May 30 2019

STATUS

approved

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Last modified April 15 09:32 EDT 2021. Contains 342977 sequences. (Running on oeis4.)