A214488 List of words over {1,3} with equal numbers of 1's and 3's.

13, 31, 1133, 1313, 1331, 3113, 3131, 3311, 111333, 113133, 113313, 113331, 131133, 131313, 131331, 133113, 133131, 133311, 311133, 311313, 311331, 313113, 313131, 313311, 331113, 331131, 331311, 333111

Offset: 1

Author

Jonathan Vos Post, Jul 18 2012

Keywords

• nonn
• base
• easy

Comments

This is to 3 as A214218 is to 2. The subsequence of primes (when interpreted as decimal integers) is A087511.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A214218.

Programs

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 *)