A023742 - OEIS

%I #13 Apr 02 2014 05:05:55

%S 27,30,39,45,54,57,75,78,99,108,114,120,135,141,147,156,177,180,198,

%T 201,210,216,225,228,267,270,291,300,306,312,387,396,432,450,456,480,

%U 519,525,531,540,561,564,579,588,624,705,708,720

%N Base 4 expansion uses each positive digit just once.

%C By definition a subset of A039562. The number 4005, for example, is in A039562 but not in here. - _R. J. Mathar_, May 23 2008

%H Vincenzo Librandi, <a href="/A023742/b023742.txt">Table of n, a(n) for n = 1..4000</a>

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

%K nonn,base,easy

%O 1,1

%A _Olivier Gérard_