A244927 - OEIS

A244927

Least positive number k such that k*n written in base 10 is either a repunit or of the form 1111....0000.

1, 5, 37, 25, 2, 185, 15873, 125, 12345679, 1, 1, 925, 8547, 79365, 74, 625, 65359477124183, 61728395, 5847953216374269, 5, 5291, 5, 48309178743961352657, 4625, 4, 42735, 4115226337448559670781893, 396825, 38314176245210727969348659, 37, 3584229390681, 3125, 3367, 326797385620915

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OFFSET

1,2

LINKS

M. F. Hasler, Table of n, a(n) for n = 1..1016 (first 100 terms from Chai Wah Wu), Mar 04 2025

FORMULA

a(n) = A244859(n)/n.

a(3^k) = (10^(3^k)-1)/3^(k+2). a(n) <= (10^n-1)/(9*n). If n > 2 is not a power of 3, then a(n) <= (10^(n-1)-1)/(9*n). - Chai Wah Wu, Mar 04 2025

EXAMPLE

For n = 7, 15873*7 = 111111 and this is the least positive multiple of 7 that is either a repunit or of the form 1111...000.

CROSSREFS

Cf. A244859, A079339, A004290. Equal to A079339 for the first 6 terms.

Sequence in context: A157809 A079339 A257343 * A043075 A096673 A144960

Adjacent sequences: A244924 A244925 A244926 * A244928 A244929 A244930

KEYWORD

nonn,base,changed

AUTHOR

Chai Wah Wu, Jul 08 2014

STATUS

approved