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 1-7 of 7 results.

A282444 Numbers k such that A282442(k) = k + 1.

Original entry on oeis.org

1, 2, 5, 8, 14, 50, 119, 200, 269, 299, 1154, 5369, 47249, 48299, 58643, 130325, 148979, 282074, 887480
Offset: 1

Views

Author

Peter Kagey, Feb 15 2017

Keywords

Comments

a(18) > 10^6. - Hakan Icoz, Apr 09 2021

Crossrefs

Cf. A282442.

Programs

  • Python
    def A282442():
        n = 0
        while True:
            n += 1
            h = n
            k = 2
            while h >= k:
                h = h % k
                h = n - h
                k += 1
            yield k
    n=0
    for i in A282442():
        n += 1
        if i == n+1:
            print(n) # Hakan Icoz, Apr 09 2021

Extensions

a(13)-a(19) from Hakan Icoz, Apr 09 2021

A282434 Positions of records in A282442.

Original entry on oeis.org

1, 2, 4, 5, 8, 11, 12, 14, 18, 19, 21, 24, 25, 28, 34, 40, 41, 50, 54, 55, 60, 63, 70, 76, 86, 87, 90, 96, 99, 107, 118, 119, 132, 139, 152, 164, 181, 184, 190, 197, 200, 208, 220, 233, 236, 237, 242, 252, 269, 272, 285, 288, 298, 299, 324, 328, 341, 354, 357
Offset: 1

Views

Author

Peter Kagey, Feb 15 2017

Keywords

Comments

Equivalently, positions of records in A282443.

Crossrefs

Cf. A282442.

A282427 Numbers k such that A282442(k) = ceiling(k/2) + 1.

Original entry on oeis.org

1, 3, 7, 39, 47, 111, 959, 3319, 7407, 11967, 13007, 16239
Offset: 1

Views

Author

Peter Kagey, Feb 15 2017

Keywords

Comments

All terms are odd.
Proof: if A282442(2m) = m + 1, then the step of length m would have to have concluded on exactly the middle step, but a phase with step-length m cannot end on the middle step because the distance from the middle step to the top/bottom of the staircase is equal to m.

Crossrefs

Cf. A282442.

A282443 a(n) is the largest step size that is taken on a staircase of n steps when following the following procedure: Take steps of length 1 up a staircase until you can't step any further, then take steps of length 2 down until you can't step any further, and so on.

Original entry on oeis.org

1, 2, 2, 3, 5, 4, 4, 8, 8, 7, 9, 10, 10, 14, 14, 10, 11, 17, 18, 15, 19, 16, 14, 23, 24, 17, 19, 27, 18, 23, 25, 20, 20, 30, 30, 19, 27, 24, 20, 31, 39, 32, 30, 38, 38, 24, 24, 34, 34, 50, 46, 31, 39, 53, 54, 47, 49, 40, 38, 59, 58, 57, 62, 58, 48, 49, 57, 39
Offset: 1

Views

Author

Peter Kagey, Feb 15 2017

Keywords

Examples

			For n = 4:
step size 1: 0 -> 1 -> 2 -> 3 -> 4;
step size 2: 4 -> 2 -> 0;
step size 3: 0 -> 3.
Because the walker cannot take four steps down, the biggest step size is 3.
Therefore a(4) = 3.
		

Crossrefs

Formula

a(n) = A282442(n) - 1.

A329231 The maximum number of times one reaches a single position during the grasshopper procedure.

Original entry on oeis.org

1, 1, 1, 1, 3, 2, 1, 1, 4, 3, 3, 3, 3, 3, 3, 1, 5, 2, 3, 3, 4, 3, 5, 3, 3, 4, 5, 3, 4, 4, 4, 1, 4, 4, 3, 4, 4, 3, 3, 5, 4, 5, 3, 3, 4, 4, 5, 4, 6, 4, 5, 4, 5, 4, 5, 4, 4, 4, 5, 5, 4, 5, 5, 1, 4, 4, 5, 3, 4, 5, 5, 4, 4, 7, 4, 4, 4, 5, 5, 5, 4, 4, 4, 4, 4, 5, 4
Offset: 1

Views

Author

Peter Kagey, Nov 08 2019

Keywords

Comments

The grasshopper procedure: n positions are evenly spaced around a circle, a grasshopper hops randomly to any position, after the k-th hop, the grasshopper looks clockwise and counterclockwise k positions. If one of the positions has been visited less often then the other, it hops there; if both positions have been visited an equal number of times, it hops k steps in the clockwise position. (See Mathematics Stack Exchange link for more details.)
a(n) >= (A329230(n)-1)/(n-1).
Least values of n such that a(n) = 1, 2, 3, etc are 1, 6, 5, 9, 17, 49, 74, 198, 688, 1745 etc.
Conjecture: a(n) = 1 if and only if n = 3, n = 7, or n = 2^k for some k.
Conjecture: The largest values of n for which a(n) = 2, 3, 4, 5 respectively are n = 18, 68, 381, 1972.
If the second conjecture is true, then 2, 3, 4, and 5 appear 2, 19, 87, and 313 times respectively.
Conjecture: Every integer greater than 1 appears in this sequence a finite number of times.

Crossrefs

A282573 The number of steps taken on a staircase of n steps during the following routine: Take steps of length 1 up a staircase until you can't step any further, then take steps of length 2 down until you can't step any further, and so on.

Original entry on oeis.org

1, 3, 4, 7, 10, 12, 13, 19, 20, 23, 26, 32, 33, 39, 40, 41, 46, 53, 57, 56, 63, 65, 66, 77, 81, 80, 83, 94, 90, 97, 100, 102, 103, 117, 118, 117, 128, 126, 127, 138, 149, 151, 152, 162, 163, 160, 161, 175, 176, 194, 195, 186, 197, 212, 216, 215, 218, 220, 221
Offset: 1

Views

Author

Peter Kagey, Feb 18 2017

Keywords

Examples

			For n = 4:
step size 1: 0 -> 1 -> 2 -> 3 -> 4 (four steps);
step size 2: 4 -> 2 -> 0 (two steps);
step size 3: 0 -> 3 (one step).
Because the walker cannot take four steps down, a(4) = 4 + 2 + 1 = 7.
		

Crossrefs

A282574 The final position on a staircase of n steps during the following routine: Take steps of length 1 up a staircase until you can't step any further, then take steps of length 2 down until you can't step any further, and so on.

Original entry on oeis.org

1, 0, 1, 3, 5, 2, 3, 0, 1, 7, 9, 2, 3, 0, 1, 6, 11, 17, 1, 15, 19, 6, 9, 23, 1, 17, 19, 27, 11, 23, 25, 12, 13, 4, 5, 19, 27, 14, 19, 31, 39, 10, 13, 6, 7, 22, 23, 14, 15, 0, 5, 31, 39, 53, 1, 47, 49, 18, 21, 59, 3, 57, 1, 6, 17, 49, 57, 39, 43, 69, 9, 47, 51
Offset: 1

Views

Author

Peter Kagey, Feb 18 2017

Keywords

Comments

If a(n) = 0 or a(n) = n, then A282443(n) = n and n is in A282444.
a(n) is bounded above by A282443(n) and bounded below by n - A282443(n).

Examples

			For n = 4:
step size 1: 0 -> 1 -> 2 -> 3 -> 4 (four steps);
step size 2: 4 -> 2 -> 0 (two steps);
step size 3: 0 -> 3 (one step).
Because the walker cannot take four steps down, a(4) = 3 (the final position).
		

Crossrefs

Showing 1-7 of 7 results.