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A072194
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Replace all prime factors p of n with n-p.
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1
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1, 0, 0, 4, 0, 12, 0, 216, 36, 40, 0, 900, 0, 84, 120, 38416, 0, 3600, 0, 4860, 252, 220, 0, 223608, 400, 312, 13824, 14196, 0, 18900, 0, 24300000, 660, 544, 840, 1258884, 0, 684, 936, 1920520, 0, 54600, 0, 58212, 70560, 1012, 0, 201485520, 1764, 97200
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OFFSET
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1,4
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COMMENTS
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a(n)=0 iff n is prime.
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LINKS
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EXAMPLE
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a(18) = a(2*3*3) = (18-2)*(18-3)*(18-3) = 16*15*15 = 3600.
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MATHEMATICA
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Join[{1}, Table[Times@@(n-#&/@Flatten[Table[#[[1]], #[[2]]]&/@FactorInteger[ n]]), {n, 2, 50}]] (* Harvey P. Dale, Dec 04 2018 *)
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PROG
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(PARI) a(n) = {my(f = factor(n)); for (k=1, #f~, f[k, 1] = n - f[k, 1]; ); factorback(f); } \\ Michel Marcus, Mar 22 2018
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CROSSREFS
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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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