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A162022
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Smallest prime factor of n-th odd composite integers A071904.
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4
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3, 3, 3, 5, 3, 3, 5, 3, 3, 7, 3, 5, 3, 3, 5, 3, 3, 7, 3, 5, 3, 7, 3, 5, 3, 3, 3, 5, 3, 7, 11, 3, 5, 3, 7, 3, 3, 11, 5, 3, 3, 5, 3, 7, 3, 13, 3, 5, 3, 3, 5, 11, 3, 3, 3, 7, 5, 3, 11, 3, 5, 7, 3, 13, 3, 3, 5, 3, 3, 5, 13, 3, 11, 3, 7, 3, 5, 3, 3, 5, 3, 3, 7, 17, 3, 5, 3, 13, 7, 3, 5, 3, 3, 11, 3, 17, 5, 3, 7, 3
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OFFSET
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1,1
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COMMENTS
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Records are for n's such that A071904(n) = squares of primes.
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LINKS
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EXAMPLE
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MATHEMATICA
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nn=501; With[{ci=Complement[Range[9, nn, 2], Prime[Range[PrimePi[nn]]]]}, FactorInteger[ #][[1, 1]]&/@ci] (* Harvey P. Dale, Nov 30 2012 *)
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PROG
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(Python)
from sympy import primepi, primefactors
if n == 1: return 3
m, k = n, primepi(n) + n + (n>>1)
while m != k:
m, k = k, primepi(k) + n + (k>>1)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Corrected example a(4)=5 Francesco Antoni (francesco_antoni(AT)yahoo.com), Aug 04 2010
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STATUS
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approved
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