A127201 Base-2 logarithms of denominators corresponding to A127200.

2, 1, 3, 5, 6, 6, 4, 7, 8, 11, 12, 11, 13, 14, 15, 17, 18, 18, 18, 16, 19, 23, 24, 25, 26, 27, 28, 26, 29, 31, 32, 33, 34, 35, 36, 36, 35, 37, 38, 41, 42, 41, 43, 44, 45, 47, 48, 49, 50, 51, 52, 52, 52, 52, 46, 53, 54, 59, 60, 58, 61, 62, 63, 64, 65, 67, 68, 69, 70, 70, 68, 73

Offset: 2

Author

Artur Jasinski, Jan 08 2007

Keywords

• nonn
• frac

Crossrefs

Cf. A119523, A127197, A127200.

Programs

Mathematica

Table[Round[(1/Log[2])Log[Denominator[Sum[PrimePi[k]/2^k, {k, 2, x}]]]], {x, 2, 100}]

PARI

a(n) = logint(denominator(sum(k=2, n, primepi(k)/2^k)), 2); \\ Michel Marcus, Oct 28 2019