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 A077189 Smallest concatenation 123...(k-1) k (k-1)...321 (a concatenation of natural numbers from 1 to k and back to 1) that is a multiple of 2n-1, or 0 if no such number exists. 3
 1, 12321, 0, 12345654321, 12321, 121, 12345654321, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(5k+3) = 0. Are there any other values of n such that a(n) = 0? The next value, 2n-1 = 17, has k = 109, for a total of 435 digits and is too large to include. - Franklin T. Adams-Watters, Jun 02 2006 LINKS Jinyuan Wang, Table of n, a(n) for n = 1..11 EXAMPLE a(5) = 12321 is a multiple of 9. CROSSREFS Cf. A077180, A077181, A077182, A077183, A077184, A077186, A077188, A077190. Cf. A120008. Sequence in context: A250856 A242716 A077186 * A277947 A321492 A237782 Adjacent sequences:  A077186 A077187 A077188 * A077190 A077191 A077192 KEYWORD nonn,base AUTHOR Amarnath Murthy, Nov 01 2002 EXTENSIONS More terms from Franklin T. Adams-Watters, Jun 02 2006 STATUS approved

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Last modified September 20 01:41 EDT 2020. Contains 337249 sequences. (Running on oeis4.)