A220846 - OEIS

%I #9 Jan 01 2013 00:03:08

%S 1,3,4,14,6,72,8,120,39,180,12,4032,14,336,360,1984,18,12636,20,16800,

%T 672,792,24,829440,155,1092,1080,43904,30,1944000,32,64512,1584,1836,

%U 1680,25474176,38,2280,2184,5760000,42,7112448,44,162624,157950,3312,48

%N a(n) = sum_(d|n) ((product_(d|n) d) / d).

%C Conjecture: sequence is injective (all terms of this sequence occur exactly once).

%H Jaroslav Krizek, <a href="/A220846/b220846.txt">Table of n, a(n) for n = 1..100</a>

%F a(n) = sum_(d|n) (A007955(n) / d).

%F a(p) = p + 1 for prime p.

%e The divisors of 6 are 1, 2, 3, 6. A007955(6) = product_(d|6) d = 1*2*3*6 = 36.

%e a(6) = 36/1 + 36/2 + 36/3 + 36/6 = 36 + 18 + 12 + 6 = 72.

%Y Cf. A007955 (product of divisors of n.).

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Dec 22 2012