OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
sort([seq(seq((10^(2*d)-1)/9+2*add(10^i, i=s), s=combinat:-choose([$0..(2*d-1)], d)), d=1..4)]); # Robert Israel, Jul 09 2018
MATHEMATICA
Flatten[Table[Sort[FromDigits/@Permutations[PadRight[{}, 2n, {1, 3}]]], {n, 3}]] (* Harvey P. Dale, Aug 03 2014 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Jonathan Vos Post, Jul 18 2012
STATUS
approved