A160758 Integer averages of first n nonprime numbers for some n.
1, 8, 25, 33, 359, 2948, 3291, 4959, 22350, 33357, 60907, 80962, 8276347, 11856980, 15254419, 176009996, 967538242, 1729774831, 9977169279, 193005936726
Offset: 1
Examples
The sum of the first 44 nonprimes is 1452. 1452 / 44 = 33, hence 33 is in the sequence.
Crossrefs
Programs
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Magma
S:=[]; a:=0; c:=0; for n in [1..40000000] do if not IsPrime(n) then a+:=n; c+:=1; if a mod c eq 0 then Append(~S, a div c); end if; end if; end for; S; // Klaus Brockhaus, Aug 11 2009
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Mathematica
lst = {}; s = 0; c = 0; k = 1; While[k < 2700000000, If[ !PrimeQ@k, c++; s = s + k; If[Mod[s, c] == 0, AppendTo[lst, s/c]]]; k++ ]; lst (* Robert G. Wilson v, Jun 05 2009 *) a=0;lst={};Do[If[ !PrimeQ[n],m=n;a+=m;If[a/n==IntegerPart[a/n],AppendTo[lst,a/n]]],{n,9!}];lst
Extensions
a(6) - a(16) from Robert G. Wilson v, Jun 05 2009
a(17) - a(19) from Donovan Johnson, Sep 16 2009
Edited by N. J. A. Sloane, May 11 2010
a(20) from Donovan Johnson, May 20 2010
Comments