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A163248
Sum of the n-th composite number plus the number of composite numbers less than the n-th noncomposite number.
1
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
OFFSET
1,1
LINKS
FORMULA
a(n) = A002808(n) + A162177(n) = A008578(n) + A073169(n).
MAPLE
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
CROSSREFS
Sequence in context: A076298 A194579 A194594 * A341280 A034288 A131984
KEYWORD
nonn,easy,less
AUTHOR
Jaroslav Krizek, Jul 23 2009
EXTENSIONS
Corrected for Aug 2009 change of offset in A158611 and A008578 by Jaroslav Krizek, Jan 27 2010
STATUS
approved