OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
FORMULA
MATHEMATICA
a[1] = 1; a[n_] := (fi = FactorInteger[n]; Times @@ ((fi[[All, 1]] + 1)^fi[[All, 2]])); Table[a[n]*3^(PrimeOmega[n]), {n, 1, 100}] (* G. C. Greubel, May 20 2016 *)
f[p_, e_] := (3*(p+1))^e; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 17 2023 *)
PROG
(PARI) a(n) = {my(f = factor(n)); for (k=1, #f~, f[k, 1] = 3*(f[k, 1]+1)); factorback(f); } \\ Michel Marcus, May 21 2016
CROSSREFS
KEYWORD
nonn,easy,mult
AUTHOR
Jaroslav Krizek, Oct 18 2009
STATUS
approved