|
Search: id:A102641
|
|
|
| A102641 |
|
Compute the greatest prime divisors [A006530(),GPD] of -j+2^n for j=0,1,...,L. a(n) is the maximal L length of such a sequence in which the greatest prime divisors are increasing with decreasing j. |
|
+0
5
|
|
| 1, 2, 2, 4, 2, 4, 2, 3, 2, 4, 2, 4, 2, 4, 2, 2, 2, 3, 2, 4, 2, 2, 2, 4, 2, 2, 2, 4, 2, 4, 2, 3, 2, 4, 4, 4, 2, 3, 4, 4, 2, 3, 2, 4, 2, 2, 2, 4, 2, 3, 2, 4, 2, 4, 6, 2, 4, 2, 2, 3, 2, 3, 3, 2, 2, 3, 2, 3, 2, 3, 2, 4, 2, 3, 6, 4, 2, 3, 2, 3, 4, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 4, 2, 4, 4, 4, 2, 3, 3, 4, 2, 4, 2, 3, 5
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
A006530(2^n)=2 is a local minimum. Going either upward or downward with the argument, the largest prime factors are increasing for a while. Here the maximal length of increasing largest-prime-divisor sequences are given when going downward with the arguments. Compare with A102640.
|
|
EXAMPLE
|
n=12: 2^10=4096. The greatest prime divisors for 4096, 4095, 4094, 4093 are as follows:{2, 13, 89, 4093}. A006530[4092]=31 is already smaller than A006530[4093]. Thus the length of increasing GPD-sequence is 4=a(12).
|
|
CROSSREFS
|
Cf. A006530, A102640, A102642, A102643, A102644.
Sequence in context: A138785 A131817 A138232 this_sequence A054763 A100374 A045841
Adjacent sequences: A102638 A102639 A102640 this_sequence A102642 A102643 A102644
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Jan 21 2005
|
|
|
Search completed in 0.005 seconds
|
