A278996 Numbers of the form (3h+1)*3^(2k)-1 or (3h+2)*3^(2k+1)-1 for h,k in N.

0, 3, 5, 6, 8, 9, 12, 14, 15, 18, 21, 23, 24, 27, 30, 32, 33, 35, 36, 39, 41, 42, 45, 48, 50, 51, 53, 54, 57, 59, 60, 62, 63, 66, 68, 69, 72, 75, 77, 78, 80, 81, 84, 86, 87, 89, 90, 93, 95, 96, 99, 102, 104, 105, 108, 111, 113, 114, 116, 117, 120, 122, 123, 126, 129, 131

Offset

1,2

Comments

n is in the sequence if and only if either n == 0, 3, 5, or 6 (mod 9) or n == 8 (mod 9) and (n-8)/9 is in the sequence. - Robert Israel, Dec 15 2016

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Hao Fu, G.-N. Han, Computer assisted proof for Apwenian sequences related to Hankel determinants, arXiv preprint arXiv:1601.04370 [math.NT], 2016. See sequence "J" in Section 2.1.

Maple

filter:= proc(n) local m;
  m:= padic:-ordp(n+1, 3);
  (n+1)/3^m mod 3 = 1 + (m mod 2)
end proc:
select(filter, [$0..100]); # Robert Israel, Dec 15 2016

Mathematica

isok[n_]:=Module[{ord=IntegerExponent[n+1, 3]}, Mod[(n+1)/3^ord, 3]==Mod[ord, 2]+1]; Select[Range[0, 131], isok](* Ray Chandler, Dec 17 2016 *)

Crossrefs

Complement of A278997.

Sequence in context: A285967 A295581 A164902 * A099441 A129359 A110801

Adjacent sequences: A278993 A278994 A278995 * A278997 A278998 A278999

Keyword

nonn

Author

N. J. A. Sloane, Dec 07 2016

Extensions

More terms from Robert Israel, Dec 15 2016

Status

approved