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).

9, 33, 333, 9999, 33333, 333333, 9999999, 11111111, 111111111, 99999999999, 3333333333333, 333333333333333, 99999999999999999, 3333333333333333333, 333333333333333333333, 99999999999999999999999

Offset

1,1

Comments

Numerators in A172496.

Links

Table of n, a(n) for n=1..16.

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

Adjacent sequences: A172495 A172496 A172497 * A172499 A172500 A172501

Keyword

nonn,base

Author

Jaroslav Krizek, Feb 05 2010

Extensions

Edited and extended by D. S. McNeil, Nov 27 2010

Status

approved