A293073 Number of matchings in the n-cocktail party graph.

1, 7, 51, 513, 6345, 93255, 1584555, 30524865, 656843985, 15605162055, 405495737955, 11435339115585, 347722239169305, 11337916544369415, 394530748734397275, 14590576590956791425, 571378543704076133025, 23617402334089770781575

Offset

1,2

Links

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

Eric Weisstein's World of Mathematics, Cocktail Party Graph

Eric Weisstein's World of Mathematics, Independent Edge Set

Eric Weisstein's World of Mathematics, Matching

Mathematica

RecurrenceTable[{4 (1 + n) (2 + n) a[n] + (4 + 10 n + 4 n^2) a[1 + n] + (-9 - 4 n) a[2 + n] + a[3 + n] == 0, a[1] == 1, a[2] == 7, a[3] == 51}, a, {n, 20}]

Crossrefs

Sequence in context: A230883 A304939 A352358 * A368286 A081216 A198087

Adjacent sequences: A293070 A293071 A293072 * A293074 A293075 A293076

Keyword

nonn

Author

Eric W. Weisstein, Sep 30 2017

Status

approved