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A214488 List of words over {1,3} with equal numbers of 1's and 3's. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

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

Cf. A214218.

Sequence in context: A247837 A227172 A180757 * A247836 A159670 A238736

Adjacent sequences:  A214485 A214486 A214487 * A214489 A214490 A214491

KEYWORD

nonn,base,easy

AUTHOR

Jonathan Vos Post, Jul 18 2012

STATUS

approved

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Last modified November 14 09:49 EST 2018. Contains 317182 sequences. (Running on oeis4.)