OFFSET
1,2
LINKS
FORMULA
Multiplicative with a(p^e) = prime(p)^prime(e). - M. F. Hasler, Nov 20 2018
Sum_{n>=1} 1/a(n) = Product_{m>=1} (1 + Sum_{k>=1} 1/prime(m)^prime(k)) = 1.22718741... . - Amiram Eldar, Jan 20 2024
EXAMPLE
a(12) = a(2^2 * 3^1) = prime(2)^prime(2) * prime(3)^prime(1) = 3^3 * 5^2 = 675.
MATHEMATICA
a[n_] := Times @@ (Prime[#[[1]]]^Prime[#[[2]]] & /@ FactorInteger[n]); a[1] = 1; Table[a[n], {n, 45}]
PROG
(PARI) a(n) = my(f=factor(n)); prod(k=1, #f~, prime(f[k, 1])^prime(f[k, 2])); \\ Michel Marcus, Nov 20 2018
(PARI) apply( A321874(n)=factorback(apply(prime, factor(n))), [1..49]) \\ M. F. Hasler, Nov 20 2018
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Ilya Gutkovskiy, Nov 20 2018
STATUS
approved