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A081926 Triangle read by rows in which n-th row gives n smallest numbers with digit sum n. 4
1, 2, 11, 3, 12, 21, 4, 13, 22, 31, 5, 14, 23, 32, 41, 6, 15, 24, 33, 42, 51, 7, 16, 25, 34, 43, 52, 61, 8, 17, 26, 35, 44, 53, 62, 71, 9, 18, 27, 36, 45, 54, 63, 72, 81, 19, 28, 37, 46, 55, 64, 73, 82, 91, 109, 29, 38, 47, 56, 65, 74, 83, 92, 119, 128, 137 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10011 (first 141 rows, flattened; first 40 rows from T. D. Noe)

EXAMPLE

Triangle starts

1

2 11

3 12 21

4 13 22 31

5 14 23 32 41

MAPLE

f:= proc(n) local Res, d, v, count;

    Res:= NULL; count:= 0;

    for d from ceil(n/9) while count < n do

       v:= g(n, d, n-count, 1);

       Res:= Res, op(v);

       count:= count + nops(v);

    od:

    Res

end proc:

g:= proc(n, d, remain) local rem, Res, j, j0, v;

      if remain = 0 then return [] else rem:= remain fi;

      if nargs = 4 then j0:= 1 else j0:= 0 fi;

      if d = 1 then if n >= j0 and n <= 9 then [n] else [] fi

      else

        Res:= NULL;

        for j from max(j0, ceil(n-9*(d-1))) to min(9, n) while rem > 0 do

          v:= map(t -> j*10^(d-1)+t, procname(n-j, d-1, rem));

          Res:= Res, op(v);

          rem:= rem - nops(v);

        od;

        [Res]

      fi

end proc:

for i from 1 to 25 do f(i) od; # Robert Israel, Feb 19 2018

MATHEMATICA

Needs["Combinatorica`"]; Table[Take[Union[Flatten[Table[FromDigits /@ Permutations[PadRight[s, 6]], {s, Partitions[n, 9]}]]], n], {n, 40}] (* T. D. Noe, Mar 08 2013 *)

CROSSREFS

Cf. A081927, A081928.

Sequence in context: A087712 A180702 A263328 * A242614 A069800 A275536

Adjacent sequences:  A081923 A081924 A081925 * A081927 A081928 A081929

KEYWORD

base,easy,nonn,tabl,look

AUTHOR

Amarnath Murthy, Apr 01 2003

STATUS

approved

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Last modified August 20 21:29 EDT 2019. Contains 326155 sequences. (Running on oeis4.)