a(n) = number of permutations of (1,2,...,n) producible by an ordered quadruple of distinct transpositions.

A253207

a(n) = number of permutations of (1,2,...,n) producible by an ordered quadruple of distinct transpositions.

Terms

    a(0) =11a(1) =59a(2) =359a(3) =1799a(4) =7091a(5) =22995a(6) =64143a(7) =159093a(8) =359348a(9) =752180a(10) =1478204a(11) =2754752a(12) =4906202a(13) =8402522a(14) =13907394a(15) =22337388a(16) =34933761a(17) =53348561a(18) =79746821a(19) =116926733a(20) =168459797a(21) =238853045a(22) =333735545a(23) =460071495a(24) =626402322a(25) =843120306a(26) =1122776354

External references