|
| |
|
|
A043569
|
|
Numbers n such that base 2 representation has exactly 2 runs.
|
|
3
| |
|
|
2, 4, 6, 8, 12, 14, 16, 24, 28, 30, 32, 48, 56, 60, 62, 64, 96, 112, 120, 124, 126, 128, 192, 224, 240, 248, 252, 254, 256, 384, 448, 480, 496, 504, 508, 510, 512, 768, 896, 960, 992, 1008, 1016, 1020, 1022, 1024, 1536, 1792, 1920, 1984, 2016, 2032, 2040, 2044
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Numbers n such that binary representation contains the bit string "10" but not "01". Subsequence of A062289; set difference A062289 minus A101082. - Rick L. Shepherd (rshepherd2(AT)hotmail.com), Nov 29 2004
Mersenne numbers (A000225) times powers of 2 (A000079). Therefore this sequence contains the even perfect numbers (A000396). - Alonso Delarte (alonso.delarte(AT)gmail.com), Apr 21 2006
|
|
|
FORMULA
| This sequence is twice A023758. - Franklin T. Adams-Watters, Apr 21 2006
|
|
|
MAPLE
| a:=proc(n) local nn, nd: nn:=convert(n, base, 2): nd:={seq(nn[j]-nn[j-1], j=2..nops(nn))}: if n=2 then 2 elif nd={0, 1} then n else fi end: seq(a(n), n=1..2100); - Emeric Deutsch, Apr 21 2006
a:=proc(n) local n2, d: n2:=convert(n, base, 2): d:={seq(n2[j]-n2[j-1], j=2..nops(n2))}: if n=2 then 2 elif d={0, 1} then n else fi end: seq(a(n), n=1..2100); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 22 2006
|
|
|
MATHEMATICA
| Take[Sort[Flatten[Table[(2^x - 1)*(2^y), {x, 32}, {y, 32}]]], 54] - Alonso Delarte (alonso.delarte(AT)gmail.com), Apr 21 2006
|
|
|
CROSSREFS
| Cf. A062289, A101082.
Sequence in context: A043748 A043756 A043765 * A010063 A089623 A089681
Adjacent sequences: A043566 A043567 A043568 * A043570 A043571 A043572
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
|
|
|
EXTENSIONS
| More terms from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Nov 29 2004
|
| |
|
|
