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 1-4 of 4 results.

A103747 Trajectory of 2 under repeated application of the map n -> A102370(n).

Original entry on oeis.org

2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 126, 130, 134, 138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 254, 258, 262, 266, 270, 274, 278, 282, 286, 290, 294, 298, 302, 306, 310, 314, 382, 386, 390, 394, 398, 402, 406, 410, 414, 418, 422
Offset: 1

Views

Author

Benoit Cloitre and David Applegate, Mar 25 2005

Keywords

Comments

Although it initially appears that a(n)-8n is the 16-periodic sequence {-2,-6,-10,-14,-18,-22,-26,-30,-34,-38,-42,-46,-50,-54,6,2}, this pattern eventually breaks down. However, the first divergence occurs beyond the first 400 million terms.
(a(n)) agrees with the 16-periodic sequence up to a(2^67-1) = 2^70 - 70, but then diverges with a(2^67) = 2^71 - 2. - Charlie Neder, Feb 07 2019

Crossrefs

Trajectories of other numbers: A103192 (1), A103621 (7), A158953 (12), A159887 (29).

Programs

  • Haskell
    a103747 n = a103747_list !! (n-1)
    a103747_list = iterate (fromInteger . a102370) 2
    -- Reinhard Zumkeller, Jul 21 2012

Extensions

Edited by Peter Munn, Jan 13 2024

A103621 Trajectory of 7 under repeated application of the map n -> A102370(n).

Original entry on oeis.org

7, 9, 11, 13, 23, 25, 27, 61, 71, 73, 75, 77, 87, 89, 91, 125, 135, 137, 139, 141, 151, 153, 155, 189, 199, 201, 203, 205, 215, 217, 219, 253, 263, 265, 267, 269, 279, 281, 283, 317, 327, 329, 331, 333, 343, 345, 347, 381, 391, 393, 395, 397, 407, 409, 411, 445
Offset: 1

Views

Author

Philippe Deléham, Mar 31 2005

Keywords

Comments

Initially, first differences are 8-periodic: 2,2,2,10,2,2,34,10. [Unsigned comment made accurate by Peter Munn, Jan 13 2024]

Crossrefs

Cf. A102370.
Trajectories of other numbers A103192 (1), A103747 (2), A158953 (12), A159887 (29).

Programs

  • Mathematica
    f[n_] := Block[{k = 1, s = 0, l = Max[2, Floor[ Log[2, n + 1] + 2]]}, While[k < l, If[ Mod[n + k, 2^k] == 0, s = s + 2^k]; k++ ]; s + n]; NestList[f, 7, 55] (* Robert G. Wilson v, Mar 30 2005 *)

Formula

Conjectures from Chai Wah Wu, Feb 01 2018: (Start)
a(n) = a(n-1) + a(n-8) - a(n-9) for n > 9.
G.f.: x*(3*x^8 + 34*x^7 + 2*x^6 + 2*x^5 + 10*x^4 + 2*x^3 + 2*x^2 + 2*x + 7)/(x^9 - x^8 - x + 1). (End)
The above conjectures are incompatible with A102370(2^37-37) = 2^38-3. - Peter Munn, Jan 13 2024

Extensions

More terms from Robert G. Wilson v, Mar 30 2005

A158953 Trajectory of 12 under repeated application of the map n -> A102370(n).

Original entry on oeis.org

12, 28, 44, 60, 76, 92, 108, 124, 140, 156, 172, 188, 204, 220, 236, 252, 268, 284, 300, 316, 332, 348, 364, 380, 396, 412, 428, 444, 460, 476, 492, 508, 524, 540, 556, 572, 588, 604, 620, 636, 652, 668, 684, 700, 716, 732, 748, 764, 780, 796, 812, 828, 844
Offset: 1

Views

Author

Philippe Deléham, Apr 01 2009

Keywords

Comments

Coincides with A098502 for at least 1400 terms. - R. J. Mathar, Apr 16 2009
Agrees with A098502 for the first 65535 terms. A098502(65535) = a(65535) = 1048556 = 2^20 - 20. A098502(65536) = 1048572 = 2^20 - 4; a(65536) = 2097148 = 2^21 - 4. - Philippe Deléham, Jan 05 2023

Crossrefs

Trajectories of other numbers: A103192 (1), A103747 (2), A103621 (7), A159887 (29).

A159888 Numbers congruent to {-5,29,39,41,43,45,55,57,59,93,103,105,107,109,119,121} mod 256.

Original entry on oeis.org

29, 39, 41, 43, 45, 55, 57, 59, 93, 103, 105, 107, 109, 119, 121, 251, 285, 295, 297, 299, 301, 311, 313, 315, 349, 359, 361, 363, 365, 375, 377, 507, 541, 551, 553, 555, 557, 567, 569, 571, 605, 615, 617, 619, 621, 631, 633, 763, 797, 807, 809, 811, 813, 823, 825
Offset: 1

Views

Author

Philippe Deléham, Apr 25 2009

Keywords

Comments

When will this first differ from A159887, the trajectory of 29 under repeated application of the map n -> A102370(n)?
A bound on the sequences starting to differ is when the appearance of 2^135 - 135 here is followed by 2^135 - 5. This is because A102370(2^135 - 135) = 2^136 - 5. - Peter Munn, Jan 12 2024

Crossrefs

Programs

  • Magma
    [n: n in [1..1000] | n mod 256 in [-5,29,39,41, 43,45,55,57,59,93,103,105,107,109,119,121,251]]; // Vincenzo Librandi, Mar 11 2014
  • Mathematica
    Select[Range[900],MemberQ[{29, 39, 41, 43, 45, 55, 57, 59, 93, 103, 105, 107, 109, 119, 121, 251}, Mod[#, 256]]&] (* Harvey P. Dale, Mar 09 2014 *)
    LinearRecurrence[{1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,-1},{29,39,41,43,45,55,57,59,93,103,105,107,109,119,121,251,285},55] (* Ray Chandler, Jul 15 2015 *)

Extensions

Corrected by Harvey P. Dale, Mar 09 2014
Edited by Peter Munn, Dec 06 2023
Showing 1-4 of 4 results.