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 A071817 Number of 3-digit numbers whose digits add up to n. 10
 1, 3, 6, 10, 15, 21, 28, 36, 45, 54, 61, 66, 69, 70, 69, 66, 61, 54, 45, 36, 28, 21, 15, 10, 6, 3, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The sequence as a whole is palindromic; a(n) = a(28-n). - Jon E. Schoenfield, Nov 19 2016 LINKS FORMULA G.f.: (1 - x^10)^2*(x - x^10)/(1 - x)^3. - Miquel Cerda, Jul 09 2017 EXAMPLE a(4) = 10 because there are 10 different 3-digit numbers whose digit sum is 4 (103, 112, 121, 130, 202, 211, 220, 301, 310, 400, which are the 3-digit elements of A052218). MAPLE for i from 1 to 9*3 do a[i] := 0:od:for i from 100 to 999 dob := convert(i, base, 10): s := sum(b[j], j=1..nops(b)):a[s] := a[s]+1:od:seq(a[j], j=1..3*9); CROSSREFS Cf. A071816. Sequence in context: A062918 A113168 A341192 * A033442 A105335 A130489 Adjacent sequences:  A071814 A071815 A071816 * A071818 A071819 A071820 KEYWORD fini,full,nonn,base AUTHOR Graeme McRae, Jun 07 2002 EXTENSIONS Corrected and extended by Sascha Kurz, Feb 07 2003 Name clarified by Jon E. Schoenfield, Nov 20 2016 STATUS approved

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Last modified May 7 23:48 EDT 2021. Contains 343652 sequences. (Running on oeis4.)