A132140 Numbers containing no zeros in ternary representation and with an initial 1.

1, 4, 5, 13, 14, 16, 17, 40, 41, 43, 44, 49, 50, 52, 53, 121, 122, 124, 125, 130, 131, 133, 134, 148, 149, 151, 152, 157, 158, 160, 161, 364, 365, 367, 368, 373, 374, 376, 377, 391, 392, 394, 395, 400, 401, 403, 404, 445, 446, 448, 449, 454, 455, 457, 458, 472

Offset: 1

Author

Reinhard Zumkeller, Aug 20 2007

Keywords

• nonn
• base
• easy

Comments

Intersection of A032924 and A132141;

A132138(A132139(a(n))) = 1.

Examples

			14 is in the sequence because its ternary representation is 112;
15 is not in the sequence because its ternary representation is 120.
		

Links

• R. Zumkeller, Table of n, a(n) for n = 1..10000
• Index entries for 3-automatic sequences.

Crossrefs

Cf. A032924, A132141, A132138, A132139, A007089.

Programs

Haskell

a132140 n = a132140_list !! (n-1)
a132140_list = filter f [1..] where
   f x = x < 3 && x == 1 || t > 0 && f x' where (x', t) = divMod x 3
-- Reinhard Zumkeller, Feb 06 2015

Maple

a:=proc(n) local nn, L: nn:=convert(n,base,3): L:=nops(nn): if nn[L]=1 and 0 < product(nn[j],j=1..L) then n else end if end proc: seq(a(n),n=1..500); # Emeric Deutsch, Sep 09 2007

Mathematica

Flatten[Table[FromDigits[Join[{1},#],3]&/@Tuples[{1,2},n],{n,0,5}]] (* Harvey P. Dale, Jan 28 2015 *)