# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a002998 Showing 1-1 of 1 %I A002998 M0489 #57 Jun 30 2023 08:19:03 %S A002998 0,1,2,3,4,5,6,7,8,9,190,209,48,247,266,195,448,476,198,874,3980,399, %T A002998 2398,1679,888,4975,1898,999,7588,4988,39990,8959,17888,42999,28798, %U A002998 57995,29988,37999,59888,49998,699880,177899,88998,99889,479996,499995 %N A002998 Smallest multiple of n whose digits sum to n. %C A002998 a(n) = A131382(n) * n. - _Michel Marcus_, Dec 10 2012 %C A002998 The subsequence of repdigits is: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 888, 999, 999999999, 999999999999999999999999999, ... and their indices are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 24, 27, 81, 243, 729, 999, ... - _Michel Marcus_, Apr 14 2015 %C A002998 a(n) is the smallest harshad number (see A005349) whose sum of digits is n; it is not obvious that a(n) exists for all n, see Mohammed Aassila's reference. - _Robert FERREOL_, Jun 30 2023 %D A002998 Mohammed Aassila, 1000 challenges mathématiques, Algèbre, Ellipses, 2016, p. 110. %D A002998 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A002998 David Wilson, Table of n, a(n) for n = 0..1000 %H A002998 H. Fredricksen, E. J. Ionascu, F. Luca, and P. Stanica, Minimal Niven numbers, arXiv:0803.0477 [math.NT], 2008. %H A002998 H. Fredricksen, E. J. Ionascu, F. Luca, and P. Stanica, Minimal Niven numbers, Acta Arithmetica 132(2008), 135-159. %H A002998 H. W. Gould, Letters to N. J. A. Sloane, 1974 %H A002998 David Wilson, C++ program %t A002998 Flatten[Table[Select[n Range[100000], Total[IntegerDigits[#]] == n&, 1], {n,0,50}]] (* _Harvey P. Dale_, Oct 30 2011 *) %o A002998 (PARI) a(n)=my(k); while(sumdigits(k+=n)!=n,); k \\ _Charles R Greathouse IV_, Feb 01 2013 %Y A002998 Cf. A005349, A131382. %K A002998 nonn,base,easy,nice %O A002998 0,3 %A A002998 _N. J. A. Sloane_ %E A002998 More terms from _Erich Friedman_, Jul 04 2001 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE