A198383 a(n) = Sum_{k=1..n} 2^(n mod k).
1, 2, 4, 5, 10, 10, 20, 22, 37, 40, 80, 72, 144, 158, 278, 283, 566, 548, 1096, 1120, 2106, 2162, 4324, 4210, 8389, 8584, 16650, 16772, 33544, 33194, 66388, 66968, 131882, 132690, 265222, 263607, 527214, 530138, 1052078, 1054254, 2108508, 2103282, 4206564, 4216760
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..1000
- Benoit Cloitre, An asymptotic formula for sum_{k=1..n}x^(n mod k) [broken link, draft]
Programs
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Mathematica
Table[Sum[2^Mod[n, k], {k, n}], {n, 44}] (* Michael De Vlieger, Oct 19 2015 *) -
PARI
a(n) = sum(k=1, n, 2^(n%k))
Formula
a(n) = 2^ceiling(n/2) + O(2^(n/3)).
Comments