If n mod 2 = 0 then m := n/2 and a(n) = (3*m)!*(5*m+1)/((m+1)!*(2*m+1)!); otherwise m := (n-1)/2, a(n) = 6*(3*m+2)!/(m!*(2*m+3)!).

A047750

If n mod 2 = 0 then m := n/2 and a(n) = (3*m)!*(5*m+1)/((m+1)!*(2*m+1)!); otherwise m := (n-1)/2, a(n) = 6*(3*m+2)!/(m!*(2*m+3)!).

Terms

    a(0) =1a(1) =2a(2) =3a(3) =6a(4) =11a(5) =24a(6) =48a(7) =110a(8) =231a(9) =546a(10) =1183a(11) =2856a(12) =6324a(13) =15504a(14) =34884a(15) =86526a(16) =197087a(17) =493350a(18) =1134705a(19) =2861430a(20) =6633315a(21) =16829280a(22) =39268320a(23) =100134216a(24) =234930276a(25) =601661144a(26) =1418201268a(27) =3645533040a(28) =8627761528a(29) =22249511328

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