A292621 a(n) = a(n-1) + a(floor(log(n))) with a(1) = 1, a(2) = 2.
1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99, 102, 105, 108, 111, 114, 117, 120, 123, 126, 129, 132, 135, 139, 143, 147, 151, 155, 159, 163, 167
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
- KeyTo9_Fans, A Chinese post discussing the sum of 1/a(i)
- Fedor Petrov, The proof of the divergence of the sum of 1/a(i), Mathoverflow, Sep 2017.
Programs
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Maple
f:= proc(n) option remember; procname(n-1)+procname(floor(log(n))) end proc: f(1):= 1: f(2):= 2: map(f, [$1..100]); # Robert Israel, Sep 28 2017
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Mathematica
a[n_] := a[n] = If[n <= 2, n, a[n - 1] + a[Floor@ Log@ n]]; Array[a, 62] (* Michael De Vlieger, Sep 21 2017 *)
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PARI
a(n) = if (n<=2, n, a(n-1) + a(floor(log(n)))); \\ Michel Marcus, Sep 21 2017
Comments