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 A000461 Concatenate n n times. 25
 1, 22, 333, 4444, 55555, 666666, 7777777, 88888888, 999999999, 10101010101010101010, 1111111111111111111111, 121212121212121212121212, 13131313131313131313131313, 1414141414141414141414141414, 151515151515151515151515151515, 16161616161616161616161616161616 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES F. Smarandache, "Properties of the numbers", Univ. of Craiova Archives, 1975; Arizona State University Special Collections, Tempe, AZ. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..333 Eric Weisstein's World of Mathematics, Smarandache Sequences FORMULA a(n) = n*(10^(n*L(n))-1)/(10^L(n)-1) where L(n) = A004216(n)+1 = floor(log_10(10n)). - Henry Bottomley, Jun 01 2000 A055642(a(n)) = n * A055642(n). - Reinhard Zumkeller, Apr 26 2011 a(n) = Sum_{i=0..n-1} (n*10^(i*(floor(log(10, n)) + 1))). - José de Jesús Camacho Medina, Dec 10 2014 EXAMPLE From Bruno Berselli, Oct 05 2018: (Start) . 1 * 9 = 09 . 22 * 9 = 198 . 333 * 9 = 2997 . 4444 * 9 = 39996 . 55555 * 9 = 499995 . 666666 * 9 = 5999994 . 7777777 * 9 = 69999993 . 88888888 * 9 = 799999992 . 999999999 * 9 = 8999999991 (End) MAPLE a:= n-> parse(cat(n\$n)): seq(a(n), n=1..20); # Alois P. Heinz, Apr 26 2011 MATHEMATICA Table[Sum[(n)*10^(i*(Floor[Log[10, n]] + 1)), {i, 0, n - 1}], {n, 1, 30}] (* José de Jesús Camacho Medina, Dec 10 2014 *) Table[FromDigits[Flatten[IntegerDigits/@Table[n, {n}]]], {n, 15}] (* Harvey P. Dale, Mar 01 2015 *) Table[FromDigits[PadRight[{}, n IntegerLength[n], IntegerDigits[n]]], {n, 15}] (* Harvey P. Dale, Jun 19 2016 *) PROG (Haskell) a000461 n = (read \$ concat \$ replicate n \$ show n) :: Integer -- Reinhard Zumkeller, Apr 26 2011 (PARI) a(n) = eval(concat(apply(x->Str(x), vector(n, k, n)))); \\ Michel Marcus, Oct 05 2018; Feb 12 2023 (Python) def a(n): return int(str(n)*n) print([a(n) for n in range(1, 17)]) # Michael S. Branicky, Jan 22 2021 CROSSREFS Cf. A048376, A053422. Sequence in context: A158849 A048376 A053422 * A216730 A048795 A068186 Adjacent sequences: A000458 A000459 A000460 * A000462 A000463 A000464 KEYWORD nonn,base,easy AUTHOR John Radu (Suttones(AT)aol.com) STATUS approved

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Last modified March 31 15:21 EDT 2023. Contains 361668 sequences. (Running on oeis4.)