Search: id:A062346 Results 1-1 of 1 results found. %I A062346 %S A062346 3,45,210,630,1485,3003,5460,9180,14535,21945,31878,44850,61425,82215, %T A062346 107880,139128,176715,221445,274170,335790,407253,489555,583740,690900, %U A062346 812175,948753,1101870,1272810,1462905,1673535,1906128,2162160,2443155 %N A062346 Consider 2n tennis players; a(n) is the number of matches needed to let every possible pair play each other. %C A062346 Number of matchings of size two (edges) in a complete graph on 2n vertices. %F A062346 Superseeker suggests a(n) = (6+25n+35n^2+20n^3+4n^4)/2, but I cannot see why this should be true. %F A062346 a(n)=n*(4n^3 - 12n^2 + 11n -3)/2. - Swapnil P. Bhatia (sbhatia(AT)cs.unh.edu), Jul 20 2006 %e A062346 a(2)=3: given players a,b,c,d, the matches needed are (ab,cd), (ac,bd), (ad,bc). %e A062346 For example, for the K_4 on vertices {0,1,2,3} the possible matchings of size two are: {{0,1}, {2,3}}, {{0,3},{1,2}} and {{0,2},{1,3}}. %Y A062346 Sequence in context: A093585 A062270 A069955 this_sequence A002682 A073595 A117972 %Y A062346 Adjacent sequences: A062343 A062344 A062345 this_sequence A062347 A062348 A062349 %K A062346 nonn %O A062346 2,1 %A A062346 Michel ten Voorde (seqfan(AT)tenvoorde.org) Jul 06 2001 %E A062346 More terms from Swapnil P. Bhatia (sbhatia(AT)cs.unh.edu), Jul 20 2006 Search completed in 0.001 seconds