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A229726 Denominator of Sum_{k=1..2n+1} 2^k/k. 4
1, 3, 15, 105, 315, 3465, 45045, 9009, 153153, 2909907, 14549535, 334639305, 1673196525, 5019589575, 145568097675, 4512611027925, 4512611027925, 4512611027925, 166966608033225, 166966608033225, 6845630929362225, 294362129962575675, 294362129962575675, 13835020108241056725, 96845140757687397075, 96845140757687397075, 5132792460157432044975 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Numerator is A108866.

LINKS

Hugo Pfoertner, Table of n, a(n) for n = 0..500

EXAMPLE

2, 20/3, 256/15, 4832/105, 42496/315, 1467392/3465, 62836736/45045, 42790912/9009, 2535587840/153153, 170851041280/2909907, 3070050172928/14549535, 256460544016384/334639305, 4697678227177472/1673196525, 52001663422038016/5019589575, ...

PROG

(PARI) for(n=0, 26, print1(denominator(sum(k=1, 2*n+1, 2^k/k)), ", ")) \\ Hugo Pfoertner, Mar 07 2020

CROSSREFS

Cf. A229727, A108866.

Sequence in context: A255427 A181131 A293996 * A145624 A025547 A220747

Adjacent sequences:  A229723 A229724 A229725 * A229727 A229728 A229729

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Sep 28 2013

STATUS

approved

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Last modified August 3 06:43 EDT 2021. Contains 346435 sequences. (Running on oeis4.)