

A279535


Triangle read by rows: The number of digits in the smallest 9repdigit that is a multiple of n and m, where n and m are coprime to 2 and 5.


0



1, 1, 1, 6, 6, 42, 1, 3, 6, 9, 2, 2, 6, 2, 22, 6, 6, 6, 6, 6, 78, 16, 16, 48, 16, 16, 48, 272, 18, 18, 18, 18, 18, 18, 144, 342, 6, 6, 42, 6, 6, 6, 48, 18, 42, 22, 22, 66, 22, 22, 66, 176, 198, 66, 506, 3, 9, 6, 27, 6, 6, 48, 18, 18, 66, 81, 28, 28, 84, 28, 28, 84, 112, 252, 84, 308, 84, 812
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OFFSET

1,4


COMMENTS

The number of digits of the smallest member of A002283 divisible by n and m, as n and m run through A045572. Numbers of the form 10^d1 are not divisible through 5 or 2, so these are excluded in the table. Losely related to A278588.


LINKS

Table of n, a(n) for n=1..78.


FORMULA

T(i,j) = min{d: (n*m)  (10^d1)} where n=A045572(i) and m=A045572(j).


EXAMPLE

The 3rd smallest number coprime to 2 and 5 is A045572(3)=7. The smallest 9repdigit divisible by 7*7=49 is 10^421 = A002283(42), to T(3,3)=42. The triangle starts
1;
1, 1;
6, 6, 42;
1, 3, 6, 9;
2, 2, 6, 2, 22;
6, 6, 6, 6, 6, 78;
16, 16, 48, 16, 16, 48,272;


CROSSREFS

Cf. A002329.
Sequence in context: A278435 A279333 A278734 * A125510 A117859 A229159
Adjacent sequences: A279532 A279533 A279534 * A279536 A279537 A279538


KEYWORD

nonn,tabl,base


AUTHOR

R. J. Mathar, Dec 14 2016


STATUS

approved



