|
|
A114971
|
|
Numbers n such that 3^n + n^3 is a semiprime.
|
|
3
|
|
|
1, 4, 8, 14, 16, 22, 23, 32, 34, 50, 52, 62, 80, 154, 170, 176, 202, 208, 214, 236, 248, 332, 398, 422
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
EXAMPLE
|
4 is OK because 3^4 + 4^3 = 81 + 64 = 145 = 5*29 (semiprime).
|
|
MATHEMATICA
|
|
|
PROG
|
(Magma)IsSemiprime:=func< n | &+[ k[2]: k in Factorization(n) ] eq 2 >; [ n: n in [1..95] | IsSemiprime(3^n+n^3)]; // Vincenzo Librandi Dec 16 2010
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more,hard
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|