A104362 Sum of divisors of A104357(n) = A104350(n) - 1.

1, 6, 12, 60, 180, 1260, 2760, 7560, 37800, 415800, 1265040, 16287864, 113538360, 567638664, 1135134000, 19298936664, 58868650320, 1113894381120, 5499724230000, 39112247205360, 423754918508832, 10054207233388032, 29220034833990000, 146100190526456640, 1915895635570469280, 5712343370808883200, 39885667247556843120

Offset: 2

Author

Reinhard Zumkeller, Mar 06 2005

Keywords

• nonn

Links

• Max Alekseyev, Table of n, a(n) for n = 2..145 (terms for n = 2..74 from Amiram Eldar)
• Reinhard Zumkeller, Products of largest prime factors of numbers <= n

Crossrefs

Cf. A000203, A104350, A104357, A104358, A104359, A104360, A104361, A104363, A104364, A104370.

Programs

Maple

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

Mathematica

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 *)

Formula

a(n) = A000203(A104357(n));

a(p) = A104350(p) for primes p.

Extensions

Corrected and extended by R. J. Mathar, Oct 30 2006