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%I #12 Dec 03 2023 05:01:33
%S 2,6,12,21,31,45,59,78,97,119,141,173,199,229,261,300,334,379,417,467,
%T 511,557,603,671,722,776,834,902,960,1040,1102,1181,1249,1319,1391,
%U 1494,1568,1646,1726,1832,1914,2022,2108,2212,2314,2408,2502,2642,2741,2854,2958,3080,3186,3324,3436
%N Partial sums of A065387.
%H N. J. A. Sloane, <a href="/A292768/b292768.txt">Table of n, a(n) for n = 1..10000</a>
%F G.f.: (1/(1 - x))*Sum_{k>=1} (mu(k) + 1)*x^k/(1 - x^k)^2. - _Ilya Gutkovskiy_, Sep 28 2017
%F a(n) = (3/(Pi^2) + Pi^2/12) * n^2 + O(n*log(n)). - _Amiram Eldar_, Dec 03 2023
%t Accumulate @ Table[EulerPhi[n] + DivisorSigma[1, n], {n, 100}] (* _Amiram Eldar_, Dec 03 2023 *)
%o (PARI) lista(nmax) = {my(f, s = 0); for(n = 1, nmax, f = factor(n); s += (sigma(f) + eulerphi(f)); print1(s, ", "));} \\ _Amiram Eldar_, Dec 03 2023
%Y Cf. A000010, A000203, A065387.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Sep 28 2017
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