login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A279535 Triangle read by rows: The number of digits in the smallest 9-repdigit 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 (list; table; graph; refs; listen; history; text; internal format)
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^d-1 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^d-1)} where n=A045572(i) and m=A045572(j).

EXAMPLE

  The 3rd smallest number coprime to 2 and 5 is A045572(3)=7. The smallest 9-repdigit divisible by 7*7=49 is 10^42-1 = 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 28 22:39 EDT 2021. Contains 346338 sequences. (Running on oeis4.)