|
| |
|
|
A064084
|
|
A multiplicative version of 2^n - 1 (A000225).
|
|
3
| |
|
|
1, 3, 7, 15, 31, 21, 127, 255, 511, 93, 2047, 105, 8191, 381, 217, 65535, 131071, 1533, 524287, 465, 889, 6141, 8388607, 1785, 33554431, 24573, 134217727, 1905, 536870911, 651, 2147483647
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Since n -> 2^n - 1 is an embedding of the ordered structure N = {1, 2, 3, ...} (the order being the "divides" relation) into itself, A064084(n) always divides A000225(n); the sequence of quotients of A000225 and A064084 is A064085.
|
|
|
FORMULA
| A064084(n) := (2^((p_1)^(e_1)) - 1) * ... * (2^((p_k)^(e_k)) - 1) where (p_1)^(e_1) * ... * (p_k)^(e_k) is the prime factorization of n.
|
|
|
EXAMPLE
| A064084(6) = (2^2 - 1) * (2^3 - 1) = 21 since 6 = 2 * 3.
|
|
|
CROSSREFS
| Cf. A000225, A064085, A064086.
Sequence in context: A062544 A120411 A069112 * A090633 A098583 A043729
Adjacent sequences: A064081 A064082 A064083 * A064085 A064086 A064087
|
|
|
KEYWORD
| mult,easy,nonn
|
|
|
AUTHOR
| Jens Voss (jens.voss(AT)poet.de), Sep 04 2001
|
| |
|
|
