|
%I #20 Apr 08 2024 01:41:58
%S 1,3,12,28,168,546,4368,9360,28800,148800,1785600,5401440,75620160,
%T 538793640,2711348640,5603453856,100862169408,303420079872,
%U 6068401597440,30380907997440,213199354368000,2362959510912000,56711028261888000,170288884313856000
%N Sum of divisors of A104350(n).
%H Amiram Eldar, <a href="/A104353/b104353.txt">Table of n, a(n) for n = 1..640</a>
%H Reinhard Zumkeller, <a href="/A104350/a104350.txt">Products of largest prime factors of numbers <= n</a>.
%F a(n) = A000203(A104350(n)).
%t DivisorSigma[1, FoldList[Times, Array[FactorInteger[#][[-1, 1]] &, 30]]] (* _Amiram Eldar_, Apr 08 2024 *)
%o (PARI) gpf(n) = {my(p = factor(n)[, 1]); p[#p];}
%o a(n) = sigma(prod(k = 2, n, gpf(k))); \\ _Amiram Eldar_, Apr 08 2024
%Y Cf. A000203, A104350, A104352, A062569.
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Mar 06 2005
%E a(14), a(21) corrected by _Georg Fischer_, Feb 28 2023
|
