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A129335
a(n) = phi(n!!) where phi is the Euler totient function. In other words, a(n) = A000010(A006882(n)).
1
1, 1, 2, 4, 8, 16, 48, 128, 432, 1024, 4320, 12288, 51840, 147456, 777600, 2359296, 12441600, 42467328, 223948800, 849346560, 4702924800, 16986931200, 103464345600, 407686348800, 2586608640000, 9784472371200, 69838433280000
OFFSET
1,3
LINKS
FORMULA
If n>2 is prime, a(n) = (n-1)*a(n-2). If n=2*p, where p is odd prime, a(n)=(n-2)*a(n-2). Otherwise, a(n) = n*a(n-2). - Max Alekseyev, May 26 2007
MATHEMATICA
Table[EulerPhi[n!! ], {n, 1, 30}] (* Stefan Steinerberger, May 30 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, May 26 2007
EXTENSIONS
More terms from Stefan Steinerberger, May 30 2007
STATUS
approved