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A230295 a(n) = Sum_{i=1..n} d(8*i+5) - Sum_{i=1..n} d(4*i+3), where d(n) = A000005(n). 3

%I

%S 0,2,0,0,4,2,2,2,2,4,6,4,2,6,4,6,8,4,4,10,8,6,10,6,8,10,10,8,8,10,12,

%T 16,10,10,14,10,12,12,10,14,18,16,12,18,18,16,18,12,12,18,16,16,20,20,

%U 22,24,18,18,22,20,20,22,16,16,26,26,26,26,22,24,24,24,24,24,26,26,32,24,26,30,28,28,28,26,26,36

%N a(n) = Sum_{i=1..n} d(8*i+5) - Sum_{i=1..n} d(4*i+3), where d(n) = A000005(n).

%H Jorge Luis Cimadevilla Villacorta, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.120.09.832">Certain inequalities associated with the divisor function</a>, Amer. Math. Monthly, 120 (2013), 832-837. (Shows that a(n) >= 0.)

%p See A230290.

%o (PARI) vector(100, n, sum(i=1, n, numdiv(8*i+5)) - sum(i=1, n, numdiv(4*i+3))) \\ _Michel Marcus_, Oct 09 2014

%Y Cf. A000005, A230290-A230296.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Oct 17 2013

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Last modified June 5 08:13 EDT 2020. Contains 334829 sequences. (Running on oeis4.)