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 A034050 Numbers with multiplicative digital root value 3. 15
 3, 13, 31, 113, 131, 311, 1113, 1131, 1311, 3111, 11113, 11131, 11311, 13111, 31111, 111113, 111131, 111311, 113111, 131111, 311111, 1111113, 1111131, 1111311, 1113111, 1131111, 1311111, 3111111, 11111113, 11111131, 11111311, 11113111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers with one 3, and zero or more 1s. - Daniel Forgues, Oct 09 2011 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 Eric Weisstein's World of Mathematics, Multiplicative Digital Root FORMULA There are n(n+1)/2 members up to 10^n, so a(n) is about 10^sqrt(2n). a(m*(m-1)/2+j+1) = (10^m-1)/9 + 2*10^j for 0 <= j < m. - Robert Israel, Sep 27 2016 MAPLE seq(seq((10^m-1)/9 + 2*10^j, j=0..m-1), m=1..10); # Robert Israel, Sep 27 2016 MATHEMATICA Sort[Flatten[Table[FromDigits/@Permutations[Join[{3}, PadRight[{}, n, 1]]], {n, 0, 8}]]] (* Harvey P. Dale, Jul 16 2012 *) PROG (Python) # through 8-digit terms print([int("1"*(d-i)+"3"+"1"*i) for d in range(8) for i in range(d+1)]) # Michael S. Branicky, Mar 13 2021 CROSSREFS Cf. A031347. Cf. A034048, A002275, A034049, A034050, A034051, A034052, A034053, A034054, A034055, A034056 (numbers having multiplicative digital roots 0-9). Sequence in context: A058264 A242905 A213970 * A107689 A339945 A154834 Adjacent sequences:  A034047 A034048 A034049 * A034051 A034052 A034053 KEYWORD nonn,base,easy AUTHOR Patrick De Geest, Sep 15 1998 STATUS approved

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Last modified April 15 10:14 EDT 2021. Contains 342977 sequences. (Running on oeis4.)