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 A345311 a(n) = Sum_{p|n, p prime} p^lcm(p,n/p). 0

%I #7 Mar 23 2023 07:37:10

%S 0,4,27,4,3125,793,823543,16,27,9766649,285311670611,531505,

%T 302875106592253,678223089233,30531927032,256,827240261886336764177,

%U 262873,1978419655660313589123979,95367431641649,558545874543637210,81402749386839765307625,20880467999847912034355032910567

%N a(n) = Sum_{p|n, p prime} p^lcm(p,n/p).

%C a(p) = Sum_{p|p} p^lcm(p,p/p) = p^p for primes p.

%H <a href="/index/Lc#lcm">Index entries for sequences related to lcm's</a>

%e a(10) = Sum_{p|10} p^lcm(p,10/p) = 2^lcm(2,5) + 5^lcm(5,2) = 2^10 + 5^10 = 9766649.

%t Table[Sum[k^LCM[k, n/k] (PrimePi[k] - PrimePi[k - 1]) (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 30}]

%K nonn

%O 1,2

%A _Wesley Ivan Hurt_, Jun 13 2021

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Last modified August 5 14:23 EDT 2024. Contains 374950 sequences. (Running on oeis4.)