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

A253171

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

Terms

    a(0) =3a(1) =12a(2) =60a(3) =240a(4) =756a(5) =1988a(6) =4572a(7) =9495a(8) =18205a(9) =32736a(10) =55848a(11) =91182a(12) =143430a(13) =218520a(14) =323816a(15) =468333a(16) =662967a(17) =920740a(18) =1257060a(19) =1689996a(20) =2240568a(21) =2933052a(22) =3795300a(23) =4859075a(24) =6160401a(25) =7739928a(26) =9643312a(27) =11921610a(28) =14631690a(29) =17836656

External references