A065132 - OEIS

%I #15 Mar 26 2021 06:31:17

%S 2,13,134,167,2239,62268,75255,135681,439867,18139940,23671044,

%T 40892256,312083956,724031017,1990127567,2144843867,2588619526,

%U 7439533243,15054156002,54892225873,69959798320,79760490898,282311798922

%N Arithmetic mean of first n terms of A008472 is an integer.

%F Integers n that divide A024924(n)=A008472(1)+A008472(2)+...+A008472(n).

%F Also, integers n that divide A024934(n).

%F Prime terms are listed in A143851.

%e Sum of first 13 terms of A008472 gives A024924(13) = 65 which is divisible by n = 13, so 13 is here: 0+2+3+2+5+5+7+2+3+7+11+5+13 = 65 = 13*5 = A024924(13).

%t s=0; Do[s=s+sp[n]; If[IntegerQ[n/25000], Print[n]]; If[IntegerQ[s/n], Print[{n, s, s/n}]], {n, 2, 4000000}] where sp[n]=A008472(n).

%Y Cf. A024924, A008472.

%K nonn

%O 1,1

%A _Labos Elemer_, Oct 15 2001

%E a(10)-a(19) from _Donovan Johnson_, Nov 22 2009

%E a(20)-a(23) from _Donovan Johnson_, Aug 31 2010