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A305800
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Filter sequence for a(prime) = constant sequences.
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60
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1, 2, 2, 3, 2, 4, 2, 5, 6, 7, 2, 8, 2, 9, 10, 11, 2, 12, 2, 13, 14, 15, 2, 16, 17, 18, 19, 20, 2, 21, 2, 22, 23, 24, 25, 26, 2, 27, 28, 29, 2, 30, 2, 31, 32, 33, 2, 34, 35, 36, 37, 38, 2, 39, 40, 41, 42, 43, 2, 44, 2, 45, 46, 47, 48, 49, 2, 50, 51, 52, 2, 53, 2, 54, 55, 56, 57, 58, 2, 59, 60, 61, 2, 62, 63, 64, 65, 66, 2, 67, 68, 69, 70, 71, 72, 73, 2, 74, 75, 76, 2, 77, 2, 78, 79, 80, 2, 81, 2, 82, 83, 84, 2, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96
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OFFSET
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1,2
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COMMENTS
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Restricted growth sequence transform of A239968.
In the following, A stands for this sequence, A305800, and S -> T (where S and T are sequence A-numbers) indicates that for all i, j: S(i) = S(i) => T(i) = T(j).
For example, the following implications hold:
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LINKS
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FORMULA
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a(1) = 1; for n > 1, a(n) = 2 for prime n, and a(n) = 1+n-A000720(n) for composite n.
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MATHEMATICA
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Join[{1}, Table[If[PrimeQ[n], 2, 1+n-PrimePi[n]], {n, 2, 150}]] (* Harvey P. Dale, Jul 12 2019 *)
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PROG
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(PARI) A305800(n) = if(1==n, n, if(isprime(n), 2, 1+n-primepi(n)));
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CROSSREFS
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Differs from A296073 for the first time at n=125, as a(125) = 96, while A296073(125) = 33.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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