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 A241217 Largest number that when multiplied by 7 produces an n-digit number. 1
 1, 14, 142, 1428, 14285, 142857, 1428571, 14285714, 142857142, 1428571428, 14285714285, 142857142857, 1428571428571, 14285714285714, 142857142857142, 1428571428571428, 14285714285714285, 142857142857142857, 1428571428571428571, 14285714285714285714 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The definition "largest number that when multiplied by 3 produces an n-digit number" gives A002277. LINKS Index entries for linear recurrences with constant coefficients, signature (11,-10,-1,11,-10). FORMULA a(n) = floor(10^n/7). - Michel Marcus, Apr 21 2014 G.f.: x*(1+3*x-2*x^2+7*x^3)/((x-1)*(10*x-1)*(x+1)*(x^2-x+1)). - Alois P. Heinz, Apr 30 2014 EXAMPLE 14*7 = 98 but 15*7 = 105 (too large) so a(2) = 14. PROG (PARI) a(n) = floor(10^n/7); \\ Michel Marcus, Apr 21 2014 CROSSREFS Cf. A020806, A002277. Sequence in context: A011547 A011548 A039916 * A159500 A167834 A238473 Adjacent sequences:  A241214 A241215 A241216 * A241218 A241219 A241220 KEYWORD nonn,base,easy AUTHOR J. Lowell, Apr 17 2014 EXTENSIONS More terms from Michel Marcus, Apr 21 2014 STATUS approved

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Last modified September 18 16:05 EDT 2020. Contains 337169 sequences. (Running on oeis4.)