|
| |
|
|
A054646
|
|
Smallest number to give 2^(2n) in a hailstone (3x + 1) sequence.
|
|
0
| |
|
|
1, 3, 21, 75, 151, 1365, 5461, 14563, 87381, 184111, 932067, 5592405, 13256071, 26512143, 357913941, 1431655765, 3817748707, 22906492245, 91625968981, 244335917283, 1466015503701, 5212499568715, 10424999137431
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| In hailstone sequences, only even powers of 2 are obtained as a final peak before descending to 1.
For n>1, the bisection of A010120. For n=3,6,7,9,12,15,16,18,19,21, we have a(n)=(4^n-1)/3, the largest possible value because one 3x+1 step produces 2^(2n). [From T. D. Noe (noe(AT)sspectra.com), Feb 19 2010]
|
|
|
REFERENCES
| J. Heleen, Final Peak Sequences for Hailstone Numbers, 1993, preprint.
|
|
|
CROSSREFS
| Sequence in context: A145658 A188667 A083564 * A109721 A067002 A110450
Adjacent sequences: A054643 A054644 A054645 * A054647 A054648 A054649
|
|
|
KEYWORD
| easy,nice,nonn
|
|
|
AUTHOR
| Jeffrey Heleen (meriaden(AT)hotmail.com), Apr 16 2000
|
| |
|
|
