cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 68 results. Next

A297030 Number of pieces in the list d(m), d(m-1), ..., d(0) of base-2 digits of n; see Comments.

Original entry on oeis.org

0, 1, 1, 2, 2, 2, 1, 2, 3, 3, 3, 3, 3, 2, 1, 2, 3, 4, 4, 4, 4, 4, 3, 3, 4, 4, 4, 3, 3, 2, 1, 2, 3, 4, 4, 5, 5, 5, 4, 4, 5, 5, 5, 5, 5, 4, 3, 3, 4, 5, 5, 5, 5, 5, 4, 3, 4, 4, 4, 3, 3, 2, 1, 2, 3, 4, 4, 5, 5, 5, 4, 5, 6, 6, 6, 6, 6, 5, 4, 4, 5, 6, 6, 6, 6, 6
Offset: 1

Views

Author

Clark Kimberling, Jan 13 2018

Keywords

Comments

The definition of "piece" starts with the base-b digits d(m), d(m-1), ..., d(0) of n. First, an *ascent* is a list (d(i), d(i-1), ..., d(i-h)) such that d(i) < d(i-1) < ... < d(i-h), where d(i+1) >= d(i) if i < m, and d(i-h-1) >= d(i-h) if i > h. A *descent* is a list (d(i), d(i-1), ..., d(i-h)) such that d(i) > d(i-1) > ... > d(i-h), where d(i+1) <= d(i) if i < m, and d(i-h-1) <= d(i-h) if i > h. A *flat* is a list (d(i), d(i-1), ..., d(i-h)), where h > 0, such that d(i) = d(i-1) = ... = d(i-h), where d(i+1) != d(i) if i < m, and d(i-h-1) != d(i-h) if i > h. A *piece* is an ascent, a descent, or a flat. Example: 235621103 has five pieces: (2,3,5,6), (6,2,1), (1,1), (1,0), and (0,3); that's 2 ascents, 2 descents, and 1 flat. For every b, the "piece sequence" includes every positive integer infinitely many times.

Examples

			Base-2 digits for 100:  1, 1, 0, 0, 1, 0, 0, so that a(100) = 6.

Links

Crossrefs

Cf. A297038, A296712 (rises and falls), A296882 (pits and peaks).
Guide to related sequences:
Base # pieces for n >= 1
2 A297030
3 A297031
4 A297032
5 A297033
6 A297034
7 A297035
8 A297036
9 A297037
10 A297038
11 A297039
12 A297040
13 A297041
14 A297042
15 A297043
16 A297044
20 A297045
60 A297046

Programs

  • Mathematica
    a[n_, b_] := Length[Map[Length, Split[Sign[Differences[IntegerDigits[n, b]]]]]];
b = 2; Table[a[n, b], {n, 1, 120}]

A296894 Numbers whose base-14 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 12 2018

Keywords

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 A296894-A296897 partition the natural numbers. See the guides at A296712 and A296882.

Examples

			The base-14 digits of 3152 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 3152 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296895, A296896.

Programs

  • Mathematica
    z = 200; b = 14;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296894 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296895 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296896 *)

A296897 Numbers whose base-15 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 12 2018

Keywords

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 A296897-A296899 partition the natural numbers. See the guides at A296712 and A296882.

Examples

			The base-15 digits of 3842 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 3842 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296898, A296899.

Programs

  • Mathematica
    z = 200; b = 15;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296897 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296898 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296899 *)

A296879 Numbers whose base-9 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 09 2018

Keywords

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 A296879-A296881 partition the natural numbers. See the guides at A296882 and A296712.

Examples

			The base-9 digits of 67 are 7,4; here #(pits) = 0 and #(peaks) = 0, so 67 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296880, A296881.

Programs

  • Mathematica
    z = 200; b = 9;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296879 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296880 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296881 *)

A296885 Numbers whose base-11 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 10 2018

Keywords

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.

Examples

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

Links

Crossrefs

Cf. A296882, A296712, A296886, A296887.

Programs

  • 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 *)

A296888 Numbers whose base-12 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 10 2018

Keywords

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 A296888-A296890 partition the natural numbers. See the guides at A296712 and A296882.

Examples

			The base-12 digits of 2030 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 2030 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296889, A296890.

Programs

  • Mathematica
    z = 200; b = 12;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296888 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296889 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296890 *)

A296891 Numbers whose base-13 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 10 2018

Keywords

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 A296891-A296894 partition the natural numbers. See the guides at A296712 and A296882.

Examples

			The base-13 digits of 2550 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 2550 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296892, A296893.

Programs

  • Mathematica
    z = 200; b = 13;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296891 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296892 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296893 *)

A296900 Numbers whose base-16 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 12 2018

Keywords

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 A296900-A296902 partition the natural numbers. See the guides at A296712 and A296882.

Examples

			The base-16 digits of 4626 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 4626 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296901, A296902.

Programs

  • Mathematica
    z = 200; b = 16;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296900 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296901 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296902 *)

A296903 Numbers whose base-20 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 12 2018

Keywords

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 A296903-A296905 partition the natural numbers.
a(n) = n for n = 1..400, but not for n = 401. See the guides at A296712 and A296882.

Examples

			The base-20 digits of 8822 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 8822 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296904, A296905.

Programs

  • Mathematica
    z = 200; b = 20;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296903 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296904 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296905 *)

A296906 Numbers whose base-60 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

Original entry on oeis.org

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
Offset: 1

Views

Author

Clark Kimberling, Jan 12 2018

Keywords

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.
a(n) = n for n = 1..3600, but not for n = 3601. See the guides at A296712 and A296882.

Examples

			The base-60 digits of 223262 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 223262 is in the sequence.

Links

Crossrefs

Cf. A296882, A296712, A296907, A296908.

Programs

  • 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 *)
Showing 1-10 of 68 results. Next

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.