

A278997


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


3



1, 2, 4, 7, 10, 11, 13, 16, 17, 19, 20, 22, 25, 26, 28, 29, 31, 34, 37, 38, 40, 43, 44, 46, 47, 49, 52, 55, 56, 58, 61, 64, 65, 67, 70, 71, 73, 74, 76, 79, 82, 83, 85, 88, 91, 92, 94, 97, 98, 100, 101, 103, 106, 107, 109, 110, 112, 115, 118, 119, 121, 124, 125, 127, 128, 130
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OFFSET

1,2


COMMENTS

n is in the sequence if and only if either n == 1, 2, 4, or 7 (mod 9) or n == 8 (mod 9) and (n8)/9 is in the sequence.  Robert Israel, Dec 18 2016


LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000
Hao Fu and G.N. Han, Computer assisted proof for Apwenian sequences related to Hankel determinants, arXiv preprint arXiv:1601.04370 [math.NT], 2016. See sequence "K" in Section 2.1.


MAPLE

filter:= proc(n) local m;
m:= padic:ordp(n+1, 3);
(n+1)/3^m mod 3 = 2  (m mod 2)
end proc:
select(filter, [$0..100]); # Robert Israel, Dec 18 2016


MATHEMATICA

isok[n_]:=Module[{ord=IntegerExponent[n+1, 3]}, Mod[(n+1)/3^ord, 3]!=Mod[ord, 2]+1]; Select[Range[0, 100], isok](* Ray Chandler, Dec 17 2016 *)


CROSSREFS

Complement of A278996.
Positions of 1's in A156595.
Sequence in context: A167206 A053223 A153383 * A342782 A295837 A321972
Adjacent sequences: A278994 A278995 A278996 * A278998 A278999 A279000


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Dec 07 2016


EXTENSIONS

More terms from Ray Chandler, Dec 17 2016


STATUS

approved



