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 A077183 Smallest number k such that the reverse concatenation of natural numbers from k to 1 is divisible by prime(n), or 0 if no such number exists. 7
 0, 2, 0, 2, 14, 15, 9, 5, 16, 4, 25, 21, 40, 67, 78, 66, 25, 111, 161, 49, 30, 15, 27, 20, 63, 98, 102, 3, 99, 92, 296, 71, 22, 367, 4, 48, 50, 91, 45, 241, 137, 258, 23, 28, 212, 40, 96, 408, 456, 110, 16, 731, 403, 667, 90, 130, 111, 458, 146, 18, 577, 276, 708 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Conjecture: a(n) > 0 for all n > 3, since prime(1) = 2 and prime(3) = 5 are the only primes whose multiples cannot end in 1. - Ryan Propper, Jul 29 2005 LINKS R. Stephan, Factors and Primes in Two Smarandache Sequences, Smar. Notions 9 (1998), pp. 4-10. EXAMPLE a(4) = 2 as 21 is divisible by prime(4) = 7. The smallest reverse concatenation of natural numbers k..1 that is divisible by prime(5) = 11 is 1413121110987654321, so a(5) = k = 14. MATHEMATICA Do[p = Prime[n]; k = 1; s = ToString[k]; While[Mod[ToExpression[s], p] > 0, k++; s = ToString[k] <> s]; Print[k], {n, 4, 50}] (* Ryan Propper *) CROSSREFS Cf. A077180, A077181, A077182, A077185. Sequence in context: A281205 A285152 A077184 * A101030 A093857 A056949 Adjacent sequences:  A077180 A077181 A077182 * A077184 A077185 A077186 KEYWORD base,nonn AUTHOR Amarnath Murthy, Nov 01 2002 EXTENSIONS Corrected and extended by Ralf Stephan, Mar 18 2003 Example clarified by Harvey P. Dale, Aug 22 2013 STATUS approved

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Last modified December 2 02:12 EST 2021. Contains 349435 sequences. (Running on oeis4.)