OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
Conjecture: a(n) = A055246(n) + 1. - Michel Marcus, Aug 24 2016
a(n) = A005823(2n). - Charles R Greathouse IV, Aug 24 2016
MATHEMATICA
Select[Range[2200], Last[IntegerDigits[#, 3]]==2&&DigitCount[#, 3, 1]==0&] (* Harvey P. Dale, Sep 09 2012 *)
FromDigits[#, 3]&/@(Join[#, {2}]&/@Tuples[{0, 2}, 7]) (* Harvey P. Dale, Jul 25 2020 *)
PROG
(PARI) is(n)=n%3==2 && setsearch(Set(digits(n, 3)), 1)==0 \\ Charles R Greathouse IV, Aug 24 2016
(PARI) a(n)=2*fromdigits(binary(2*n-1), 3) \\ Charles R Greathouse IV, Aug 24 2016
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
N. J. A. Sloane, May 15 2011
STATUS
approved