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 A048330 Numbers that are repdigits in base 5. 4
 0, 1, 2, 3, 4, 6, 12, 18, 24, 31, 62, 93, 124, 156, 312, 468, 624, 781, 1562, 2343, 3124, 3906, 7812, 11718, 15624, 19531, 39062, 58593, 78124, 97656, 195312, 292968, 390624, 488281, 976562, 1464843, 1953124, 2441406, 4882812, 7324218, 9765624 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..400 Eric Weisstein's World of Mathematics, Repdigit. FORMULA Conjecture: G.f.: x*(1+2*x+3*x^2+4*x^3) / ( (x-1)*(1+x)*(x^2+1)*(5*x^4-1) ) with a(n) = 6*a(n-4) - 5*a(n-8). - R. J. Mathar, Mar 15 2015 Sum_{n>=1} 1/a(n) = (25/3) * A248722 = 2.51444877998310381623... - Amiram Eldar, Jan 21 2022 EXAMPLE 12_10 = 22_5, 18_10 = 33_5, 7812_10 = 222222_5. MATHEMATICA Union[Flatten[Table[FromDigits[PadRight[{}, n, d], 5], {n, 0, 40}, {d, 4}]]] (* Vincenzo Librandi, Feb 06 2014 *) PROG (Magma) [0] cat [k:k in [1..10^7]| #Set(Intseq(k, 5)) eq 1]; // Marius A. Burtea, Oct 11 2019 CROSSREFS Cf. A010785, A033018, A028987, A028988, A248722. Sequence in context: A140494 A048316 A037393 * A118651 A206292 A129297 Adjacent sequences:  A048327 A048328 A048329 * A048331 A048332 A048333 KEYWORD nonn,base AUTHOR Patrick De Geest, Feb 15 1999 EXTENSIONS Offset changed from 1 to 0 by Vincenzo Librandi, Feb 06 2014 STATUS approved

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Last modified August 13 18:03 EDT 2022. Contains 356107 sequences. (Running on oeis4.)