|
|
A132705
|
|
For an integer n with prime factorization (p_1)*(p_2)*(p_3)* ... *(p_k), a(n) = (p_1+2)*(p_2+2)*(p_3+2)* ... *(p_k+2).
|
|
0
|
|
|
2, 3, 4, 5, 16, 7, 20, 9, 64, 25, 28, 13, 80, 15, 36, 35, 256, 19, 100, 21, 112, 45, 52, 25, 320, 49, 60, 125, 144, 31, 140, 33, 128, 65, 76, 63, 400, 49, 84, 75, 448, 43, 180, 45, 208, 175, 100, 49, 1280, 81, 196, 95, 240, 55, 500, 91, 576, 105, 124, 60
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
COMMENTS
|
a(0)=2 and a(1)=3 by convention. For an integer n with prime factorization prime(i_1)*prime(i_2)*prime(i_3)* ... *prime(i_k), a(n) = A052147(i_1)*A052147(i_2)*A052147(i_3)* ... *A052147(i_k). This sequence is to p+2 as A064478 is to p+1 for primes p.
If a(1) were 1 rather than 3, the sequence would be completely multiplicative with a(p) = p + 2. - Charles R Greathouse IV, Sep 02 2009
|
|
LINKS
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|