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A085275
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Sum of n-th composite number and its largest prime divisor.
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0
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6, 9, 10, 12, 15, 15, 21, 20, 18, 21, 25, 28, 33, 27, 30, 39, 30, 35, 35, 34, 44, 51, 42, 39, 57, 52, 45, 49, 55, 50, 69, 51, 56, 55, 68, 65, 57, 66, 63, 76, 87, 65, 93, 70, 66, 78, 77, 85, 92, 77, 75, 111, 80, 95, 88, 91, 85, 84, 123, 91, 102, 129, 116, 99, 95, 104, 115, 124
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OFFSET
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4,1
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LINKS
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EXAMPLE
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For 91=7*13 we have 91+13 = 104; for 92=2*2*23 we have 92+23 = 115.
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PROG
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(PARI) cminusp3(n) = { for(x=2, n, forstep(p=x, 2, -1, if(isprime(p) & x%p==0 & isprime(x)==0, print1(x+p, ", "); break); ) ) }
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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