A032817 Numbers whose set of base-5 digits is {1,4}.

1, 4, 6, 9, 21, 24, 31, 34, 46, 49, 106, 109, 121, 124, 156, 159, 171, 174, 231, 234, 246, 249, 531, 534, 546, 549, 606, 609, 621, 624, 781, 784, 796, 799, 856, 859, 871, 874, 1156, 1159, 1171, 1174, 1231, 1234, 1246, 1249, 2656

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for 5-automatic sequences.

Formula

a(1)=1, a(2)=4; a(n) = 5*a(floor(n/2))+1 for n odd, otherwise a(n) = 5*a(floor((n-1)/2))+4. - Bruno Berselli, May 28 2012

Mathematica

Flatten[Table[FromDigits[#, 5]&/@Tuples[{1, 4}, n], {n, 5}]] (* Vincenzo Librandi, May 27 2012 *)

Prog

(Magma) [n: n in [1..3000] | Set(IntegerToSequence(n, 5)) subset {1, 4}]; // Vincenzo Librandi, May 27 2012
(Maxima) a[1]:1$ a[2]:4$ a[n]:= if oddp(n) then 5*a[floor(n/2)]+1 else 5*a[floor((n-1)/2)]+4$ makelist(a[n], n, 1, 47); /* Bruno Berselli, May 28 2012 */

Crossrefs

Sequence in context: A120712 A115698 A039566 * A357741 A115681 A257842

Adjacent sequences: A032814 A032815 A032816 * A032818 A032819 A032820

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved