|
| |
|
|
A119972
|
|
Flag n when the first difference of the decimal encoding of the Gray code is negative.
|
|
4
| |
|
|
1, 2, -3, 4, 5, -6, -7, 8, 9, 10, -11, -12, 13, -14, -15, 16, 17, 18, -19, 20, 21, -22, -23, -24, 25, 26, -27, -28, 29, -30, -31, 32, 33, 34, -35, 36, 37, -38, -39, 40, 41, 42, -43, -44, 45, -46, -47, -48, 49, 50, -51, 52, 53, -54, -55, -56, 57, 58, -59, -60, 61, -62, -63, 64, 65, 66, -67, 68, 69, -70, -71, 72, 73, 74, -75
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
FORMULA
| Merge A091072 with minus A091067 maintaining increasing absolute value.
|
|
|
EXAMPLE
| A003188 begins 0 1 3 2 6 7 5 4 12 13 15 14 10 11 9 8 24 ...so
A055975 begins 1 2-1 4 1-2-1 8 1 2 -1 -4 1 -2-1 16 ...
so the negative positions are located at 3,6,7,11,12,14,..., = A091067
and the positive positions at the complement of A091067 which is A091072.
|
|
|
MAPLE
| isA091067 := proc(n) option remember ; if n mod 4 = 3 then RETURN(true) ; else if n mod 2 = 0 then if isA091067(n/2) then RETURN(true) ; fi ; fi ; RETURN(false) ; fi ; end: A119972 := proc(n) if isA091067(n) then -n ; else n ; fi ; end: for n from 1 to 180 do printf("%d, ", A119972(n)) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 14 2007
|
|
|
CROSSREFS
| Cf. A003188, A055975, A091067, A091072.
Sequence in context: A114142 A020725 * A131738 A000027 A001477 A087156
Adjacent sequences: A119969 A119970 A119971 * A119973 A119974 A119975
|
|
|
KEYWORD
| easy,sign
|
|
|
AUTHOR
| Alford Arnold (Alford1940(AT)aol.com), Jun 01 2006
|
|
|
EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 14 2007
|
| |
|
|
