%I #13 Jun 30 2017 03:02:37
%S 0,0,0,0,0,2,0,0,4,10,0,8,8,16,8,16,0,16,0,16,32,64,0,32,80,128,224,
%T 320,256,352,64,128,256,512,256,640,640,1024,512,1280,512,1024,512,
%U 1024,2560,3328,1280,2432,2432,3584,3584,5120,2048,2816,2048,4096,8192
%N Number of non-unitary divisors of binomial(n, floor(n/2)).
%F a(n) = A048105(A001405(n)).
%F a(n) = A000005(n) - A034444(n).
%e At n = 10, binomial(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.
%t Table[Function[k, DivisorSum[k, 1 &, ! CoprimeQ[#, k/#] &]]@ Binomial[n, Ceiling[n/2]], {n, 57}] (* _Michael De Vlieger_, Jun 29 2017 *)
%Y Cf. A000005, A001405, A034444, A048105.
%K nonn
%O 1,6
%A _Labos Elemer_
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