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A172498
a(n) = denominator of fraction a/b, where gcd(a, b) = 1, whose decimal representation has the form 0.(1)(2)(3)...(n-1)(n)... with period (1)(2)(3)...(n-1)(n).
4
9, 33, 333, 9999, 33333, 333333, 9999999, 11111111, 111111111, 99999999999, 3333333333333, 333333333333333, 99999999999999999, 3333333333333333333, 333333333333333333333, 99999999999999999999999
OFFSET
1,1
COMMENTS
Numerators in A172496.
EXAMPLE
a(10) = 99999999999; 12345678910 / 99999999999 = 0.1234567891012345678910... (period 12345678910).
PROG
(Sage)
def A172498(n):
s = ''.join(str(i) for i in range(1, n+1))
f = Integer(s) / (10**len(s)-1)
return f.denominator()
[A172498(i) for i in range(1, 15)]
CROSSREFS
Cf. A172496 (numerators), A172499, A172505.
Sequence in context: A063423 A183939 A145952 * A276284 A275695 A145925
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Feb 05 2010
EXTENSIONS
Edited and extended by D. S. McNeil, Nov 27 2010
STATUS
approved