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A278996 Numbers of the form (3h+1)*3^(2k)-1 or (3h+2)*3^(2k+1)-1 for h,k in N. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 18 06:02 EDT 2021. Contains 345098 sequences. (Running on oeis4.)