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%I #26 Oct 03 2022 17:14:01
%S 1,6,12,60,180,1260,2760,7560,37800,415800,1265040,16287864,113538360,
%T 567638664,1135134000,19298936664,58868650320,1113894381120,
%U 5499724230000,39112247205360,423754918508832,10054207233388032,29220034833990000,146100190526456640,1915895635570469280,5712343370808883200,39885667247556843120
%N Sum of divisors of A104357(n) = A104350(n) - 1.
%H Max Alekseyev, <a href="/A104362/b104362.txt">Table of n, a(n) for n = 2..145</a> (terms for n = 2..74 from Amiram Eldar)
%H Reinhard Zumkeller, <a href="/A104350/a104350.txt">Products of largest prime factors of numbers <= n</a>
%F a(n) = A000203(A104357(n));
%F a(p) = A104350(p) for primes p.
%p A000142 := proc(n) RETURN(n!) ; end: A006530 := proc(n) local i, t1, t2, t3, t4; if n = 1 then RETURN(1) ; else t1 := numtheory[divisors](n); t2 := convert(t1, list); t3 := sort(t2); t4 := nops(t3); for i from 1 to t4 do if isprime(t3[t4+1-i]) then RETURN(t3[t4+1-i]); fi; od; RETURN(1); fi ; end: A104350 := proc(n) local k,resul ; resul := 1 ; for k from 1 to n do resul := resul*A006530(k) ; od ; RETURN(resul) ; end: A104357 := proc(n) A104350(n)-1 ; end: A104362 := proc(n) numtheory[sigma](A104357(n)) ; end: for n from 2 to 30 do printf("%d,",A104362(n)) ; od ; # _R. J. Mathar_, Oct 30 2006
%t a[n_] := DivisorSigma[1, Product[FactorInteger[k][[-1, 1]], {k, 1, n}]-1]; Table[a[n], {n, 2, 23}] (* _Jean-François Alcover_, Feb 10 2018 *)
%Y Cf. A000203, A104350, A104357, A104358, A104359, A104360, A104361, A104363, A104364, A104370.
%K nonn
%O 2,2
%A _Reinhard Zumkeller_, Mar 06 2005
%E Corrected and extended by _R. J. Mathar_, Oct 30 2006
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