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A296908 Numbers n whose base-60 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments. 4
3720, 3721, 3780, 3781, 3782, 3840, 3841, 3842, 3843, 3900, 3901, 3902, 3903, 3904, 3960, 3961, 3962, 3963, 3964, 3965, 4020, 4021, 4022, 4023, 4024, 4025, 4026, 4080, 4081, 4082, 4083, 4084, 4085, 4086, 4087, 4140, 4141, 4142, 4143, 4144, 4145, 4146, 4147 (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 A296906..A296908 partition the natural numbers. We have a(n) = A000027(n) for n=1..3600, but not for n = 3601. See the guides at A296712 and A296882.

LINKS

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

EXAMPLE

The base-60 digits of 13395721 are 1,2,1,2,1; here #(pits) = 1 and #(peaks) = 2, so that 13395721 is in the sequence.

MATHEMATICA

z = 200; b = 60;

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

Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296906 *)

Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296907 *)

Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296908 *)

CROSSREFS

Cf. A296882, A296712, A296906, A296907.

Sequence in context: A180396 A158917 A252421 * A237736 A289512 A260860

Adjacent sequences: A296905 A296906 A296907 * A296909 A296910 A296911

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling, Jan 12 2018

STATUS

approved

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Last modified December 2 07:06 EST 2022. Contains 358493 sequences. (Running on oeis4.)