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A157671
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Numbers whose ternary representation begins with 2.
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2
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2, 6, 7, 8, 18, 19, 20, 21, 22, 23, 24, 25, 26, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184
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history;
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OFFSET
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1,1
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COMMENTS
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Comment [From R. J. Mathar, Mar 03 2009] (Start)
If we look at the first differences, that is
2,4,1,1,10,1,1,1,1,1,1,1,1,28,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,82,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
we obtain the records in A034472. (End)
Subsequence of A134026; A171960(a(n)) < a(n). [From Reinhard Zumkeller, Jan 20 2010]
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LINKS
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Table of n, a(n) for n=1..63.
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FORMULA
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A number n is a term iff 2*3^m <= n <= 3^(m+1)-1, for m=0,1,2,...
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MAPLE
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for n from 1 to 300 do dgs := convert(n, base, 3) ; if op(-1, dgs) = 2 then printf("%d, ", n) ; fi; od: [From R. J. Mathar, Mar 03 2009]
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MATHEMATICA
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Flatten[(Range[2*3^#, 3^(#+1)-1])&/@Range[0, 4]]
Select[Range[200], First[IntegerDigits[#, 3]]==2&] (* Harvey P. Dale, Oct 16 2012 *)
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PROG
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(PARI) s=[]; for(n=0, 4, for(x=3^n, 2*3^n-1, s=concat(s, x))); s
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CROSSREFS
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Cf. A132141.
Sequence in context: A063291 A088225 A165775 * A196747 A102046 A019913
Adjacent sequences: A157668 A157669 A157670 * A157672 A157673 A157674
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KEYWORD
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base,nonn
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AUTHOR
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Zak Seidov, Mar 04 2009
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STATUS
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approved
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