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A032911 Numbers whose set of base 4 digits is {1,3}. 2
1, 3, 5, 7, 13, 15, 21, 23, 29, 31, 53, 55, 61, 63, 85, 87, 93, 95, 117, 119, 125, 127, 213, 215, 221, 223, 245, 247, 253, 255, 341, 343, 349, 351, 373, 375, 381, 383, 469, 471, 477, 479, 501, 503, 509, 511, 853, 855, 861, 863, 885 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers that have ones in all even bit positions, counted from least significant bit as position 0. - Ralf Stephan, Nov 01 2003

LINKS

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

FORMULA

a(2n) = 4a(n) + 1, a(2n+1) = 4a(n) + 3. - Ralf Stephan, Nov 01 2003

EXAMPLE

Sequence in binary: 1 11 101 111 1101 1111 10101 10111 11101 11111..

MATHEMATICA

Flatten[Table[FromDigits[#, 4]&/@Tuples[{1, 3}, n], {n, 5}]] (* Vincenzo Librandi, May 31 2012 *)

PROG

(MAGMA) [n: n in [1..1000] | Set(IntegerToSequence(n, 4)) subset {1, 3}]; // Vincenzo Librandi, May 31 2012

CROSSREFS

Sequence in context: A063241 A007591 A097687 * A157834 A192110 A246026

Adjacent sequences:  A032908 A032909 A032910 * A032912 A032913 A032914

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified June 15 16:13 EDT 2019. Contains 324142 sequences. (Running on oeis4.)