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 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 (list; graph; refs; listen; history; text; internal format)
 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 (n-8)/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

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Last modified May 29 05:00 EDT 2022. Contains 354122 sequences. (Running on oeis4.)