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 A326279 Number of labeled n-vertex simple graphs containing either a crossing or a nesting pair of edges. 6
 0, 0, 0, 0, 28, 864, 32064, 2094064 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Two edges {a,b}, {c,d} are crossing if a < c < b < d or c < a < d < b, and nesting if a < c < d < b or c < a < b < d. LINKS FORMULA A006125(n) = a(n) + A326244(n). EXAMPLE The a(4) = 28 edge-sets:   {13,24}  {12,13,24}  {12,13,14,23}  {12,13,14,23,24}  {12,13,14,23,24,34}   {14,23}  {12,14,23}  {12,13,14,24}  {12,13,14,23,34}            {13,14,23}  {12,13,23,24}  {12,13,14,24,34}            {13,14,24}  {12,13,24,34}  {12,13,23,24,34}            {13,23,24}  {12,14,23,24}  {12,14,23,24,34}            {13,24,34}  {12,14,23,34}  {13,14,23,24,34}            {14,23,24}  {13,14,23,24}            {14,23,34}  {13,14,23,34}                        {13,14,24,34}                        {13,23,24,34}                        {14,23,24,34} MATHEMATICA croXQ[stn_]:=MatchQ[stn, {___, {x_, y_}, ___, {z_, t_}, ___}/; x

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Last modified May 28 18:24 EDT 2022. Contains 354122 sequences. (Running on oeis4.)