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A298861
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Rank of n-th prime when all the primes and twice-primes are jointly ranked.
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2
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1, 2, 4, 6, 8, 9, 11, 12, 14, 16, 17, 19, 21, 22, 24, 25, 27, 28, 30, 31, 32, 34, 36, 38, 40, 41, 42, 44, 45, 46, 49, 50, 52, 53, 56, 57, 58, 60, 62, 63, 65, 66, 67, 68, 70, 71, 74, 77, 79, 80, 81, 82, 83, 84, 86, 88, 89, 90, 92, 94, 95, 96, 99, 100, 101
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OFFSET
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1,2
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LINKS
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EXAMPLE
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A001751 = ordered sequence of primes and twice-primes: 2,3,4,5,6,7,10,... in which the primes occupy ranks 1,2,4,6,...
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MATHEMATICA
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z = 1000; u = Prime[Range[z]]; w = Take[Union[u, 2 u], z];
p[n_] := If[MemberQ[u, w[[n]]], 0, 1];
t = Table[p[n], {n, 1, z}];
Flatten[Position[t, 0]]; (* A298861 *)
Flatten[Position[t, 1]]; (* A298862 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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