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A036296 Denominator of Sum i/2^i, i=1..n. 4
1, 2, 1, 8, 8, 32, 8, 128, 128, 512, 256, 2048, 2048, 8192, 1024, 32768, 32768, 131072, 65536, 524288, 524288, 2097152, 524288, 8388608, 8388608, 33554432, 16777216, 134217728, 134217728, 536870912, 33554432, 2147483648, 2147483648, 8589934592, 4294967296 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Sum_{i>=0} i/2^i = 2. - Alonso del Arte, Aug 15 2012

REFERENCES

C. C. Clawson, The Beauty and Magic of Numbers. New York: Plenum Press (1996): 95

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

A. F. Horadam, Oresme numbers, Fib. Quart., 12 (1974), 267-271.

EXAMPLE

a(4) = 8 because 1/2 + 2/4 + 3/8 + 4/16 = 1/2 + 1/2 + 3/8 + 1/4 = 1 + 5/8 = 13/8.

MATHEMATICA

Table[Denominator[Sum[i/2^i, {i, n}]], {n, 40}] (* Alonso del Arte, Aug 08 2012 *)

PROG

(PARI) concat(1, vector(100, n, denominator(sum(i=1, n, i/2^i)))) \\ Colin Barker, Nov 09 2014

(MAGMA) [1] cat [Denominator(&+[i/2^i: i in [1..n]]): n in [1..40]]; // Vincenzo Librandi, Nov 09 2014

CROSSREFS

Cf. A036295 (numerators).

Sequence in context: A254794 A086657 A188922 * A078105 A075513 A284211

Adjacent sequences:  A036293 A036294 A036295 * A036297 A036298 A036299

KEYWORD

nonn,frac,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified February 18 05:35 EST 2019. Contains 320245 sequences. (Running on oeis4.)