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%I #12 Dec 02 2015 05:23:31
%S 1,4,7,6,12,28,15,13,18,39,28,42,24,60,60,18,39,72,42,72,63,91,60,91,
%T 42,96,56,90,72,195,63,48,124,120,124,93,60,168,120,120,96,252,84,168,
%U 168,195,124,126,93,168,195,144,120,224,195,195,186
%N a(n) = sigma(usigma(n)), where usigma(n) is the sum of unitary divisors of n (A034448) and sigma(n) is the sum of the divisors (A000203).
%H Harry J. Smith, <a href="/A063845/b063845.txt">Table of n, a(n) for n=1..1000</a>
%F a(n) = A000203(A034448(n)). - _Michel Marcus_, Dec 02 2015
%t usigma[n_] := DivisorSum[n, Boole[CoprimeQ[#, n/#]]*#& ]; a[n_] := DivisorSigma[1, usigma[n]]; Array[a, 60] (* _Jean-François Alcover_, Dec 02 2015 *)
%o (PARI) usigma(n) = sumdiv(n, d, if(gcd(d, n/d)==1, d)) { for (n=1, 1000, write("b063845.txt", n, " ", sigma(usigma(n))) ) } \\ _Harry J. Smith_, Sep 01 2009
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Oct 30 2001
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