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A135680
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a(n) = n if n = 1 or if n is prime. Otherwise, n = 4 if n is even and n = 5 if n is odd.
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3
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1, 2, 3, 4, 5, 4, 7, 4, 5, 4, 11, 4, 13, 4, 5, 4, 17, 4, 19, 4, 5, 4, 23, 4, 5, 4, 5, 4, 29, 4, 31, 4, 5, 4, 5, 4, 37, 4, 5, 4, 41, 4, 43, 4, 5, 4, 47, 4, 5, 4, 5, 4, 53, 4, 5, 4, 5, 4, 59, 4, 61, 4, 5, 4, 5, 4, 67, 4, 5, 4, 71, 4, 73
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Table[Which[n == 1, 1, PrimeQ[n], n, EvenQ[n], 4, True, 5], {n, 80}] (* Harvey P. Dale, Jul 22 2012 *)
Table[If[PrimeQ[n] || n == 1, n, If[EvenQ[n], 4, 5]], {n, 25}] (* G. C. Greubel, Oct 26 2016 *)
Join[{1, 2}, Table[Boole[PrimeQ[n]] * (n - 1) + Boole[Not[PrimeQ[n]]] * 4 + Boole[OddQ[n]], {n, 3, 80}]] (* Alonso del Arte, Oct 26 2016 *)
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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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