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a(n) = Sum_{d|n} d*2^(n-d).
5

%I #10 Oct 18 2020 08:00:18

%S 1,4,7,20,21,94,71,328,457,1194,1035,7052,4109,17294,33807,83984,

%T 65553,389650,262163,1484820,1949717,4216854,4194327,29409304,

%U 22020121,67215386,119799835,350453788,268435485,1755807774,1073741855

%N a(n) = Sum_{d|n} d*2^(n-d).

%H Vaclav Kotesovec, <a href="/A090879/b090879.txt">Table of n, a(n) for n = 1..3000</a>

%F G.f.: Sum_{m>0} m*x^m/(1-(2*x)^m).

%t f[n_] := Block[{d = Divisors[n]}, Apply[Plus, d*2^(n - d)]]; Table[ f[n], {n, 1, 32}] (* _Robert G. Wilson v_, Feb 16 2004 *)

%Y Cf. A074854, A083413.

%K easy,nonn

%O 1,2

%A _Vladeta Jovovic_, Feb 14 2004

%E More terms from _Robert G. Wilson v_, Feb 16 2004