A023742 Base 4 expansion uses each positive digit just once.

27, 30, 39, 45, 54, 57, 75, 78, 99, 108, 114, 120, 135, 141, 147, 156, 177, 180, 198, 201, 210, 216, 225, 228, 267, 270, 291, 300, 306, 312, 387, 396, 432, 450, 456, 480, 519, 525, 531, 540, 561, 564, 579, 588, 624, 705, 708, 720

Offset: 1

Author

Olivier Gérard

Keywords

• nonn
• base
• easy

Comments

By definition a subset of A039562. The number 4005, for example, is in A039562 but not in here. - R. J. Mathar, May 23 2008

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..4000

Programs

Mathematica

Union[ Map[ Plus@@(Array[ (4^#)&, Length[ # ], 0 ]*#)&, Flatten[ Table[ Permutations[ Join[ Range[ 4-1 ], Array[ 0&, k ] ] ], {k, 0, 2} ], 1 ] ] ]