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A111936 Denominator of n-th term of the harmonic series after having removed all terms containing in decimal representation a 9. 1
1, 2, 6, 12, 60, 20, 140, 280, 280, 3080, 9240, 120120, 120120, 40040, 80080, 1361360, 12252240, 2450448, 2450448, 2450448, 56360304, 56360304, 1409007600, 1409007600, 4227022800, 4227022800, 4227022800, 131037706800, 262075413600 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numerator = A111935;

A111935(n)/a(n) ---> C with C<80.

REFERENCES

G. Polya and G. Szego, Problems and Theorems in Analysis I (Springer 1924, reprinted 1972), Part One, Chap. 3, sect. 4, Problem 124.

LINKS

Table of n, a(n) for n=1..29.

EXAMPLE

n=9: 1/1+1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/10 = 789/280, therefore a(9) = 280.

MATHEMATICA

Denominator[Accumulate[DeleteCases[Table[1/n, {n, 40}], _?(MemberQ[ IntegerDigits[ Denominator[#]], 9]&)]]] (* Harvey P. Dale, Mar 05 2013 *)

CROSSREFS

Cf. A002805, A007095.

Sequence in context: A083001 A285079 A119862 * A232090 A203811 A002805

Adjacent sequences:  A111933 A111934 A111935 * A111937 A111938 A111939

KEYWORD

nonn,base,frac

AUTHOR

Reinhard Zumkeller, Aug 22 2005

STATUS

approved

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Last modified September 16 06:38 EDT 2019. Contains 327090 sequences. (Running on oeis4.)