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Table of n, a(n) for n=1..57.
At n=10, he C(10,5) = 252=4*9*7 has 18 divisors, 8 are unitary and the residual 10 are non-unitary; thus a[ 10 ]=10=18-8.
A048105 applied to terms of A001405.
Sequence in context: A197007 A011449 A231037 * A159814 A169774 A057611
Adjacent sequences: A048240 A048241 A048242 * A048244 A048245 A048246