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A174936 a(n) = Sum_{d|n} A007955(d) * A007955(n/d), where A007955(m) = product of divisors of m. 1

%I #8 Sep 08 2022 08:45:51

%S 1,4,6,20,10,84,14,160,63,220,22,3648,26,420,480,2368,34,11988,38,

%T 16480,924,1012,46,671424,275,1404,1620,44800,58,1621860,62,70656,

%U 2244,2380,2520,20190816,74,2964,3120,5154240,82,6226836,86,172480,183870,4324,94,510973440,735,251500

%N a(n) = Sum_{d|n} A007955(d) * A007955(n/d), where A007955(m) = product of divisors of m.

%H Andrew Howroyd, <a href="/A174936/b174936.txt">Table of n, a(n) for n = 1..1000</a>

%e For n = 4, A007955(n) = b(n): a(4) = b(1)*b(4/1) + b(2)*b(4/2) + b(4)*b(4/4) = 1*8 + 2*2 + 8*1 = 20.

%o (PARI) a(n)={sumdiv(n, d, vecprod(divisors(d))*vecprod(divisors(n/d)))} \\ _Andrew Howroyd_, Jan 05 2020

%o (Magma) [&+[&*Divisors(d)*&*Divisors(n div d):d in Divisors(n)]:n in [1..50]]; // _Marius A. Burtea_, Jan 05 2020

%Y Cf. A007955.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Apr 02 2010

%E Terms a(31) and beyond from _Andrew Howroyd_, Jan 05 2020

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Last modified March 28 05:39 EDT 2024. Contains 371235 sequences. (Running on oeis4.)