a(n) = phi(n!!) where phi is the Euler totient function. In other words, a(n) = A000010(A006882(n)).

A129335

a(n) = phi(n!!) where phi is the Euler totient function. In other words, a(n) = A000010(A006882(n)).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =16a(6) =48a(7) =128a(8) =432a(9) =1024a(10) =4320a(11) =12288a(12) =51840a(13) =147456a(14) =777600a(15) =2359296a(16) =12441600a(17) =42467328a(18) =223948800a(19) =849346560a(20) =4702924800a(21) =16986931200a(22) =103464345600a(23) =407686348800

External references