A065132 Arithmetic mean of first n terms of A008472 is an integer.

2, 13, 134, 167, 2239, 62268, 75255, 135681, 439867, 18139940, 23671044, 40892256, 312083956, 724031017, 1990127567, 2144843867, 2588619526, 7439533243, 15054156002, 54892225873, 69959798320, 79760490898, 282311798922

Offset

1,1

Links

Table of n, a(n) for n=1..23.

Formula

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

Also, integers n that divide A024934(n).

Prime terms are listed in A143851.

Example

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).

Mathematica

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).

Crossrefs

Cf. A024924, A008472.

Sequence in context: A223075 A239748 A355113 * A047856 A246875 A242004

Adjacent sequences: A065129 A065130 A065131 * A065133 A065134 A065135

Keyword

nonn

Author

Labos Elemer, Oct 15 2001

Extensions

a(10)-a(19) from Donovan Johnson, Nov 22 2009

a(20)-a(23) from Donovan Johnson, Aug 31 2010

Status

approved