A172503 a(n) = numerator of fraction a/b, where gcd(a, b) = 1, whose decimal representation has the form (n).(n)(n)(n)... with period (n).

10, 20, 10, 40, 50, 20, 70, 80, 10, 1000, 100, 400, 1300, 1400, 500, 1600, 1700, 200, 1900, 2000, 700, 200, 2300, 800, 2500, 2600, 300, 2800, 2900, 1000, 3100, 3200, 100, 3400, 3500, 400, 3700, 3800, 1300, 4000, 4100, 1400, 4300, 400, 500, 4600, 4700, 1600, 4900, 5000

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..10000

Example

a(10) = 1000; 1000/99 = 10.10101010... (period 10).
a(9) = 10; 10/1 = 9.9999999...

Prog

(PARI) a(n) = my(qd = #digits(n)); numerator(n / (10^(qd)-1)) * 10^qd \\ David A. Corneth, Apr 28 2019

Crossrefs

Cf. A172504 (denominators).

Sequence in context: A255529 A023916 A297353 * A107859 A294069 A249585

Adjacent sequences: A172500 A172501 A172502 * A172504 A172505 A172506

Keyword

nonn,frac,easy

Author

Jaroslav Krizek, Feb 05 2010

Extensions

More terms from David A. Corneth, Apr 28 2019

Status

approved