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 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 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

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