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A072033
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Smallest x > 0 such that gcd(2^x, A004086(2^x)) = 2^n.
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0
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4, 1, 2, 3, 26, 131, 227, 301, 567, 879, 3240, 11051, 8048, 38911, 7321, 97309, 108190, 6294, 138124, 4675268, 2687104, 1336154, 5774420
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OFFSET
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1,1
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COMMENTS
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a(14)=7321, a(17)=6294.
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LINKS
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FORMULA
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a(n) = min{x: gcd(2^x, reverse(2^x))=2^n} = min{x: A055483(x)=2^n}.
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EXAMPLE
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n=4: a(4)=26 because gcd(2^26, reverse(2^26)) = gcd(67108864, 46880176) = 16 = 2^n.
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MATHEMATICA
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a[n_] := Block[{k=1}, While[ IntegerExponent[ GCD[2^k, FromDigits@ Reverse@ IntegerDigits[2^k]], 2] != n, k++]; k]; Array[a, 13, 0] (* Giovanni Resta, Oct 28 2019 *)
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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EXTENSIONS
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Offset corrected, missing a(3) and a(13)-a(22) added by Giovanni Resta, Oct 28 2019
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STATUS
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approved
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