A097254 Numbers whose set of base 8 digits is {0,7}.

0, 7, 56, 63, 448, 455, 504, 511, 3584, 3591, 3640, 3647, 4032, 4039, 4088, 4095, 28672, 28679, 28728, 28735, 29120, 29127, 29176, 29183, 32256, 32263, 32312, 32319, 32704, 32711, 32760, 32767, 229376, 229383, 229432, 229439, 229824

Offset

1,2

Comments

n such that there exists a permutation p_1, ..., p_n of 1, ..., n such that i + p_i is a power of 8 for every i.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

Formula

a(n) = 7*A033045(n-1).

a(2n-1) = 8*a(n), a(2n) = 8*a(n)+7.

Mathematica

fQ[n_]:=Union@Join[{0, 7}, IntegerDigits[n, 8]]=={0, 7}; Select[Range[0, 300000], fQ] (* Vincenzo Librandi, May 25 2012 *)
FromDigits[#, 8]&/@Tuples[{0, 7}, 6] (* Harvey P. Dale, Aug 10 2021 *)

Prog

(Magma) [n: n in [0..250000] | Set(IntegerToSequence(n, 8)) subset {0, 7}]; // Vincenzo Librandi, May 25 2012
(Maxima) a[1]:0$ a[n]:=8*a[floor((n+1)/2)]+7*(1+(-1)^n)/2$ makelist(a[n], n, 1, 37); /* Bruno Berselli, May 25 2012 */
(PARI) a(n) = 7*fromdigits(binary(n-1), 8) \\ Rémy Sigrist, Dec 06 2018

Crossrefs

Cf. A001196, A005823, A097251-A097262.

Sequence in context: A116120 A056719 A038855 * A043911 A044526 A153797

Adjacent sequences: A097251 A097252 A097253 * A097255 A097256 A097257

Keyword

nonn,base

Author

Ray Chandler, Aug 03 2004

Status

approved