A078159 a(n) = A055086(2^n).

2, 3, 4, 7, 10, 15, 21, 31, 44, 63, 89, 127, 180, 255, 361, 511, 723, 1023, 1447, 2047, 2895, 4095, 5791, 8191, 11584, 16383, 23169, 32767, 46339, 65535, 92680, 131071, 185362, 262143, 370726, 524287, 741454, 1048575, 1482909, 2097151, 2965819, 4194303, 5931640, 8388607

Offset: 1

Author

Labos Elemer, Nov 27 2002

Keywords

• nonn

Comments

a(2n-2)=2^n-1 and a(n)=2a(n-2)+1 generally.

Crossrefs

Cf. A055086, A078160, A078161, A078162.

Programs

Mathematica

Table[ Length[ Union[ Table[ Floor[2^w/j], {j, 1, 2^w}]]], {w, 1, 25}]

PARI

a(n) = ceil(2*sqrt(2^n+1)) - 2; \\ Michel Marcus, Sep 02 2019

Extensions

Extended by Robert G. Wilson v, Dec 02 2002

More terms from Michel Marcus, Sep 02 2019