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Search: id:A098957
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| A098957 |
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Decimal value of the reverse binary expansion of the prime numbers. |
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+0
6
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| 1, 3, 5, 7, 13, 11, 17, 25, 29, 23, 31, 41, 37, 53, 61, 43, 55, 47, 97, 113, 73, 121, 101, 77, 67, 83, 115, 107, 91, 71, 127, 193, 145, 209, 169, 233, 185, 197, 229, 181, 205, 173, 253, 131, 163, 227, 203, 251, 199, 167, 151, 247, 143, 223, 257, 449, 353, 481, 337
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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15 of the first 16 terms happen to be prime. As terms increase, the preponderance of primes apparently decreases.
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REFERENCES
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Weisstein, Eric W. "Gray Code." http : // mathworld.wolfram.com/GrayCode.html
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FORMULA
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a(n) = Decimal(reverse(Binary(p(n)))) where p(n) is the n-th prime.
a(n)=GrayCodeBinarySum[Prime[n]). - Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Oct 21 2008
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EXAMPLE
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a(14)=53 because the 14th prime is 43, or 101011 binary; reverse of 101011 is 110101, or 53 decimal.
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MATHEMATICA
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GrayCodeList[k_] := Module[{b = IntegerDigits[k, 2], i}, Do[ If[b[[i - 1]] == 1, b[[i]] = 1 - b[[i]]], {i, Length[b], 2, -1} ]; b ]; a[n_] := GrayCodeList[Prime[n]]; Table[Sum[a[n][[m + 1]]*2^m, {m, 0, Length[a[n]] - 1}], {n, 1, 200}] - Roger L. Bagula and Gary W. Adamson (rlbagulatftn(AT)yahoo.com), Oct 21 2008
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CROSSREFS
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Sequence in context: A137576 A161329 A111745 this_sequence A143245 A018205 A121047
Adjacent sequences: A098954 A098955 A098956 this_sequence A098958 A098959 A098960
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KEYWORD
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base,nonn
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AUTHOR
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Gil Broussard (kikiriki(AT)mindspring.com), Oct 21 2004
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