A172499 a(n) = numerator of fraction whose decimal representation is (n).(1)(2)(3)...(n-1)(n)... with repeating part (1)(2)(3)...(n-1)(n).

10, 70, 1040, 41230, 170780, 2041150, 71234560, 90260630, 1013717420, 1012345678900, 37078189297000, 4041152263033700, 1312345678910111200, 47078189297003707100, 5041152263033704043800, 1612345678910111213141500, 19026063099001235701572400

Offset

1,1

Comments

Sequence of denominators: 9, 33, 333, 9999, 33333, 333333, 9999999, 11111111, 111111111, 99999999999, 3333333333333, ... Conjecture: this sequence is not equal to the sequence A172498.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..368

Example

a(10) = 1012345678900; 1012345678900 / 99999999999 = 10.1234567891012345678910... (repeating 12345678910).

Maple

a:= n-> (m-> numer(n+m*sum(10^(-i*length(m)), i=1..infinity))
         )(parse(cat(seq(i, i=1..n)))):
seq(a(n), n=1..19);  # Alois P. Heinz, Mar 31 2022

Crossrefs

Cf. A172500.

Sequence in context: A126505 A038779 A246427 * A215295 A136856 A016218

Adjacent sequences: A172496 A172497 A172498 * A172500 A172501 A172502

Keyword

nonn,base,frac

Author

Jaroslav Krizek, Feb 05 2010

Extensions

More terms from Alois P. Heinz, Mar 31 2022

Status

approved