login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A296885 Numbers n whose base-11 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments. 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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 A296885-A296887 partition the natural numbers. See the guides at A296712 and A296882.

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..10000

EXAMPLE

The base-11 digits of 1586 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so that 1586 is in the sequence.

MATHEMATICA

z = 200; b = 11;

d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];

Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296885 *)

Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296886 *)

Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296887 *)

CROSSREFS

Cf. A296882, A296712, A296886, A296887.

Sequence in context: A266279 A296879 A296882 * A296888 A296891 A296894

Adjacent sequences:  A296882 A296883 A296884 * A296886 A296887 A296888

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling, Jan 10 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 22:38 EDT 2021. Contains 347609 sequences. (Running on oeis4.)