OFFSET
0,2
COMMENTS
n such that there exists a permutation p_1, ..., p_n of 1, ..., n such that i + p_i is a power of 13 for every i.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = 12*A033049(n).
a(2n) = 13*a(n), a(2n+1) = a(2n)+12.
MATHEMATICA
f[n_] := FromDigits[ IntegerDigits[n, 2] /. {1 -> 12}, 13]; Array[f, 33, 0] (* or much slower *)
fQ[n_] := Union@ Join[{0, 12}, IntegerDigits[n, 13]] == {0, 12}; Select[ Range[0, 4455516 ], fQ] (* Robert G. Wilson v, May 12 2012 *)
FromDigits[#, 13]&/@Tuples[{0, 12}, 5] (* Vincenzo Librandi, Jun 04 2012 *)
PROG
(Magma) [n: n in [0..4500000] | Set(IntegerToSequence(n, 13)) subset {0, 12}]; // Vincenzo Librandi, Jun 04 2012
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Ray Chandler, Aug 03 2004
STATUS
approved