editing
approved
editing
approved
a(n) ~ 3^(n+1) / (4*n). - Vaclav Kotesovec, Nov 02 2023
approved
editing
editing
approved
Alois P. Heinz, <a href="/A054192/b054192.txt">Table of n, a(n) for n = 0..1000</a>
with(numtheory):
b:= proc(n) option remember; ceil(add(
phi(d)*2^(n/d)/(2*n), d=divisors(n))+
`if`(n::odd, 2^((n-1)/2), 2^(n/2-1)+2^(n/2-2)))
end:
a:= n-> add(b(n-j)*binomial(n, j), j=0..n):
seq(a(n), n=0..30); # Alois P. Heinz, Jul 17 2017
1, 3, 8, 20, 49, 119, 289, 705, 1731, 4283, 10690, 26934, 68531, 176115, 457110, 1198128, 3170607, 8468277, 22818167, 61999531, 169778889, 468292663, 1300270333, 3632269293, 10202425207, 28798822159, 81652955889, 232429744843, 663969970203, 1902716831527
proposed
editing
editing
proposed
a29[n_] := If[n == 0, 1, DivisorSum[n, EulerPhi[#]*2^(n/#)&]/(2*n) + If[OddQ[n], 2^((n-1)/2), 2^(n/2-1) + 2^(n/2-2)]]; a[n_] := Sum[Binomial[n, k] * a29[k], {k, 0, n}]; Array[a, 28, 0] (* Jean-François Alcover, Jul 17 2017 *)
approved
editing
_N. J. A. Sloane (njas(AT)research.att.com), _, Apr 29 2000
nonn,new
nonn
N. J. A. Sloane (njas, (AT)research.att.com), Apr 29 2000
Binomial transform of A000029.
1, 3, 8, 20, 49, 119, 289, 705, 1731, 4283, 10690, 26934, 68531, 176115, 457110, 1198128, 3170607, 8468277, 22818167, 61999531, 169778889, 468292663, 1300270333, 3632269293, 10202425207, 28798822159, 81652955889, 232429744843
0,2
nonn
njas, Apr 29 2000
approved