A000801 a(n) = Sum_{k = 1..n} floor(2^k / k).

2, 4, 6, 10, 16, 26, 44, 76, 132, 234, 420, 761, 1391, 2561, 4745, 8841, 16551, 31114, 58708, 111136, 211000, 401650, 766372, 1465422, 2807599, 5388709, 10359735, 19946715, 38459505, 74250899, 143524565, 277742293, 538043341, 1043333611, 2025040421

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

References

• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• T. D. Noe, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A000799.

Programs

Maple

A000801 := proc(n) local k; sum(floor(2^k/k),k=1..n); end;

Mathematica

Table[Sum[Floor[2^k/k], {k, n}], {n, 30}] (* T. D. Noe, Jun 20 2012 *)