|
|
A304253
|
|
Numbers k such that k = Product (p_j^e_j) = Sum (prime(p_j)^e_j).
|
|
1
|
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
EXAMPLE
|
68 is a term because 68 = 2^2*17 = prime(1)^2*prime(7) = prime(prime(1))^2 + prime(prime(7)).
8248 is a term because 8248 = 2^3*1031 = prime(1)^3*prime(173) = prime(prime(1))^3 + prime(prime(173)).
|
|
MATHEMATICA
|
a[n_] := Plus @@ (Prime[#[[1]]]^#[[2]] & /@ FactorInteger[n]); Select[Range[10000], a[#] == # &]
|
|
PROG
|
(PARI) isok(n) = my(f=factor(n)); n == sum(k=1, #f~, prime(f[k, 1])^f[k, 2]); \\ Michel Marcus, May 09 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|