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A066859 Product of sums of divisors and non-divisors. 1

%I #20 Feb 05 2021 07:27:01

%S 0,0,8,21,54,108,160,315,416,666,648,1400,1078,1944,2304,3255,2430,

%T 5148,3400,7056,6368,7812,6048,14400,9114,12978,13520,19600,12150,

%U 28296,14848,29295,24624,29214,27936,52325,25270,40860,40544,65700,34398,77472,39688

%N Product of sums of divisors and non-divisors.

%C A000203(n) + A024816(n) = A000217(n).

%H David A. Corneth, <a href="/A066859/b066859.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A000203(n)*A024816(n).

%p a:= n-> (s-> s*(n*(n+1)/2-s))(numtheory[sigma](n)):

%p seq(a(n), n=1..45); # _Alois P. Heinz_, Feb 05 2021

%o (PARI) a(n) = my(s=sigma(n)); s*(n*(n+1)/2 - s); \\ _Michel Marcus_, Feb 05 2021

%Y Cf. A000203, A024816, A000217.

%K nonn

%O 1,3

%A _Reinhard Zumkeller_, Jan 23 2002

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)