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A163248
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Sum of the n-th composite number plus the number of composite numbers less than the n-th noncomposite number.
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1
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4, 6, 8, 10, 12, 17, 20, 24, 26, 31, 38, 40, 46, 51, 53, 57, 63, 69, 72, 79, 83, 85, 91, 95, 102, 110, 114, 117, 122, 124, 128, 143, 147, 153, 155, 165, 168, 174, 180, 184, 190, 197, 200, 210, 212, 216, 218, 231, 243, 247
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listen;
history;
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internal format)
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OFFSET
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1,1
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LINKS
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FORMULA
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MAPLE
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nnc:= 1: nc:= 0; b[nnc]:= 0:b[0]:= 0:
for x from 2 to 1000 do
if isprime(x) then
nnc:= nnc+1; b[nnc]:= b[nnc-1];
else
b[nnc]:= b[nnc]+1;
nc:= nc+1;
c[nc]:= x;
fi
od:
seq(b[n-1]+c[n], n=1..min(nnc, nc)); # Robert Israel, Jan 09 2015
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CROSSREFS
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KEYWORD
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nonn,easy,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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