cp's OEIS Frontend

A160758 Integer averages of first n nonprime numbers for some n.

%I A160758 #12 Sep 08 2022 08:45:45
%S A160758 1,8,25,33,359,2948,3291,4959,22350,33357,60907,80962,8276347,
%T A160758 11856980,15254419,176009996,967538242,1729774831,9977169279,
%U A160758 193005936726
%N A160758 Integer averages of first n nonprime numbers for some n.
%C A160758 A variant of A050248 for nonprimes.
%C A160758 Numbers n such that (1/n)*sum(j=1..n, A018252(j)) is an integer. - _Robert G. Wilson v_, Jun 05 2009
%F A160758 a(n) = A164280(n) / A129749(n).
%e A160758 The sum of the first 44 nonprimes is 1452. 1452 / 44 = 33, hence 33 is in the sequence.
%t A160758 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 *)
%t A160758 a=0;lst={};Do[If[ !PrimeQ[n],m=n;a+=m;If[a/n==IntegerPart[a/n],AppendTo[lst,a/n]]],{n,9!}];lst
%o A160758 (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
%Y A160758 Cf. A050248, integer averages of n primes for some n.
%Y A160758 Cf. A018252, A051349, A164280, A129749.
%K A160758 nonn,more
%O A160758 1,2
%A A160758 _Daniel Tisdale_, May 25 2009
%E A160758 a(6) - a(16) from _Robert G. Wilson v_, Jun 05 2009
%E A160758 a(17) - a(19) from _Donovan Johnson_, Sep 16 2009
%E A160758 Edited by _N. J. A. Sloane_, May 11 2010
%E A160758 a(20) from _Donovan Johnson_, May 20 2010