A172496 a(n) = numerator 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).

1, 4, 41, 1234, 4115, 41152, 1234567, 1371742, 13717421, 12345678910, 411522630337, 41152263033704, 12345678910111213, 411522630337040438, 41152263033704043805, 12345678910111213141516, 137174210112346812683513, 13717421011234681268351302

Offset

1,2

Comments

Denominators in A172498.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..369

Example

a(10) = 12345678910; 12345678910/99999999999 = 0.1234567891012345678910... (period 12345678910).

Maple

a:= n-> (m-> numer(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

Sequence in context: A327026 A244751 A022515 * A059730 A006825 A333731

Adjacent sequences: A172493 A172494 A172495 * A172497 A172498 A172499

Keyword

nonn,base

Author

Jaroslav Krizek, Feb 05 2010

Extensions

More terms from Alois P. Heinz, Mar 31 2022

Status

approved