A214521 List of words over {1,4} with equal numbers of 1's and 4's.

14, 41, 1144, 1414, 1441, 4114, 4141, 4411, 111444, 114144, 114414, 114441, 141144, 141414, 141441, 144114, 144141, 144411, 411144, 411414, 411441, 414114, 414141, 414411, 441114, 441141, 441411, 444111, 11114444, 11141444

Offset

1,1

Comments

This is to 4 as A214488 is to 3, and as A214218 is to 2. The subsequence of primes (when interpreted as decimal integers) is A087512.

Links

Table of n, a(n) for n=1..30.

Mathematica

Sort[FromDigits/@Flatten[Table[Permutations[PadRight[{}, 2n, {1, 4}]], {n, 4}], 1]] (* Harvey P. Dale, Aug 30 2016 *)

Crossrefs

Cf. A214218, A214488.

Sequence in context: A044007 A366480 A199710 * A064512 A118237 A326624

Adjacent sequences: A214518 A214519 A214520 * A214522 A214523 A214524

Keyword

nonn,base

Author

Jonathan Vos Post, Jul 19 2012

Status

approved