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!)
A296863 Numbers whose base-3 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments. 4
15, 16, 42, 43, 45, 48, 49, 84, 87, 88, 123, 124, 126, 129, 130, 135, 136, 137, 138, 141, 142, 144, 147, 148, 149, 150, 151, 165, 168, 169, 204, 205, 246, 249, 250, 252, 258, 259, 261, 264, 265, 327, 330, 331, 366, 367, 369, 372, 373, 378, 379, 380, 381, 384 (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 A296861-A296863 partition the natural numbers. See the guides at A296882 and A296712.
LINKS
EXAMPLE
The base-3 digits of 384 are 1, 1, 2, 0, 2, 0; here #(pits) = 1 and #(peaks) = 2, so 384 is in the sequence.
MATHEMATICA
z = 200; b = 3;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296861 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296862 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296863 *)
CROSSREFS
Sequence in context: A041452 A041450 A042867 * A269459 A041462 A041464
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 July 19 16:24 EDT 2024. Contains 374410 sequences. (Running on oeis4.)