The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A296877 Numbers whose base-8 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments. 4
65, 66, 67, 68, 69, 70, 71, 129, 130, 131, 132, 133, 134, 135, 138, 139, 140, 141, 142, 143, 193, 194, 195, 196, 197, 198, 199, 202, 203, 204, 205, 206, 207, 211, 212, 213, 214, 215, 257, 258, 259, 260, 261, 262, 263, 266, 267, 268, 269, 270, 271, 275, 276 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A pit is an index i such that d(i-1) > d(i) < d(i+1); a peak is an index i such that d(i-1) < d(i) > d(i+1). The sequences A296876-A296878 partition the natural numbers. See the guides at A296882 and A296712.
LINKS
EXAMPLE
The base-8 digits of 276 are 4,2,4; here #(pits) = 1 and #(peaks) = 0, so 276 is in the sequence.
MATHEMATICA
z = 200; b = 8;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296876 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296877 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296878 *)
CROSSREFS
Sequence in context: A299559 A130764 A043625 * A044875 A174928 A355313
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Jan 09 2018
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 27 02:41 EDT 2024. Contains 372847 sequences. (Running on oeis4.)