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 82 results. Next

A352204 Indices of records in A109812.

Original entry on oeis.org

1, 2, 3, 5, 7, 8, 11, 15, 18, 21, 23, 27, 29, 32, 38, 40, 50, 53, 56, 59, 70, 75, 84, 89, 101, 103, 106, 108, 113, 156, 161, 163, 164, 188, 239, 293, 307, 328, 417, 420, 425, 431, 433, 480, 491, 546, 617, 631, 633, 648, 649, 651, 890, 892, 1225, 1235, 1245, 1251, 1305, 1307, 1315, 1323, 1324, 1476, 1485, 1517, 1598, 1891, 1898, 1913, 1970
Offset: 1

Views

Author

N. J. A. Sloane and Chai Wah Wu, Mar 28 2022

Keywords

Crossrefs

Programs

A352203 Records in A109812.

Original entry on oeis.org

1, 2, 4, 8, 10, 16, 18, 32, 33, 36, 40, 48, 64, 66, 72, 96, 128, 129, 130, 132, 136, 192, 193, 194, 196, 256, 257, 320, 322, 328, 384, 448, 512, 528, 640, 768, 770, 800, 1024, 1025, 1028, 1029, 1280, 1281, 1312, 1536, 1538, 1544, 1792, 1793, 2048, 2304, 2560, 2688, 3072, 3073, 3074, 3136, 3200, 3328, 3584, 3592, 4096, 4100, 4101, 4104, 4160, 5120
Offset: 1

Views

Author

N. J. A. Sloane and Chai Wah Wu, Mar 28 2022

Keywords

Crossrefs

Programs

A113233 Inverse permutation to A109812.

Original entry on oeis.org

1, 2, 4, 3, 6, 9, 16, 5, 10, 7, 20, 12, 26, 14, 28, 8, 13, 11, 22, 19, 24, 30, 39, 17, 33, 36, 41, 44, 51, 54, 76, 15, 18, 25, 43, 21, 37, 34, 48, 23, 31, 60, 80, 46, 57, 85, 104, 27, 66, 62, 71, 64, 90, 83, 109, 68, 88, 100, 102, 74, 112, 107, 162, 29, 35, 32, 45, 42, 61, 67
Offset: 1

Views

Author

Reinhard Zumkeller, Oct 19 2005

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List (elemIndex); import Data.Maybe (fromJust)
    a113233 = (+ 1) . fromJust . (`elemIndex` a109812_list)
    -- Reinhard Zumkeller, Sep 15 2014

Formula

A113234(n) = a(a(n)).

Extensions

a(63) corrected by Reinhard Zumkeller, Sep 15 2014

A305370 Index of 2^n in A109812.

Original entry on oeis.org

1, 2, 3, 5, 8, 15, 29, 50, 103, 164, 417, 649, 1324, 2684, 5348, 10226, 21298, 41538, 84652, 165034, 322262, 646648, 1283556, 2584860, 5163368, 10271638, 20566708, 40308350, 80758553, 161522919, 322519008, 637135132
Offset: 0

Views

Author

N. J. A. Sloane, Jun 02 2018

Keywords

Comments

It would be nice to have a formula for a(n).
The data suggests that a(n) is growing very roughly like 2^n/3.261. - N. J. A. Sloane, Mar 29 2022

Examples

			A109812(15) = 32 = 2^5, so a(5) = 15.
		

Crossrefs

Extensions

a(14)-a(22) from Chai Wah Wu, Jun 04 2018
a(23)-a(24) from Giovanni Resta, Jun 06 2018
a(25)-a(26) from Rémy Sigrist, Dec 05 2021
a(27)-a(28) from Walter Trump, Apr 13 2022
a(29)-a(31) from Walter Trump, Apr 26 2022

A352336 Define a sequence B = {b(i): i >= 1} by b(i) = smallest unused number when A109812(i) is being calculated, and then remove duplicates from B.

Original entry on oeis.org

1, 2, 3, 5, 6, 7, 11, 13, 15, 22, 23, 27, 28, 29, 30, 31, 43, 46, 47, 55, 61, 63, 87, 91, 93, 94, 95, 123, 125, 126, 127, 189, 191, 222, 223, 235, 237, 238, 239, 247, 251, 254, 255, 319, 373, 375, 379, 381, 383, 431, 439, 443, 446, 447, 475, 479, 495, 499, 503, 506, 507, 509, 511, 765, 767, 895, 959, 989, 991, 1007, 1023, 1503, 1519, 1531, 1535, 1783
Offset: 1

Views

Author

Michael De Vlieger, Mar 29 2022

Keywords

Comments

Might be called the local minima in A109812.
Also indices of records in A113233. These are the numbers that are the slowest to appear in A109812. They arrive late in A109812 because of having few zeros in their binary expansion. Every number of the form 2^k - 1 is necessarily a member, since any number less than 2^k - 1 must occur earlier in A109812. - David Broadhurst, Aug 17 2022

Examples

			The initial terms of A109812 and the smallest missing numbers (smn):
  n a(n) smn
  1  1   2
  2  2   3
  3  4   3
  4  3   5
  5  8   5
  6  5   6
  7  10  6
  8  16  6
  9   6  7
  10  9  7
  11  18 7
  12  12 7
  ...
so the distinct smallest missing numbers are 1, 2, 3, 5, 6, 7, ...
		

Crossrefs

Programs

  • Mathematica
    c[_] = 0; a[1] = c[1] = 1; u = 2; {1}~Join~Reap[Do[k = u; While[Nand[c[k] == 0, BitAnd[a[i - 1], k] == 0], k++]; If[a[i - 1] == u, Sow[u]; While[c[u] > 0, u++]]; Set[{a[i], c[k]}, {k, i}], {i, 2, nn}]][[-1, -1]]

Extensions

Edited by N. J. A. Sloane, Apr 26 2022 and May 03 2024

A352359 Indices of local minima in A109812.

Original entry on oeis.org

1, 2, 4, 6, 9, 16, 20, 26, 28, 30, 39, 41, 44, 51, 54, 76, 80, 85, 104, 109, 112, 162, 165, 175, 179, 197, 240, 294, 308, 323, 418, 423, 434, 481, 490, 500, 510, 536, 547, 632, 634, 647, 650, 699, 767, 782, 805, 883, 891, 914, 952, 996, 1009, 1226, 1269, 1271, 1314, 1316, 1322, 1325, 1477, 1483, 1892, 1901, 2419, 2588, 2685, 2803, 2936, 2988, 3555, 3570, 3833
Offset: 1

Views

Author

Michael De Vlieger, Mar 29 2022

Keywords

Comments

These are the indices (in A109812) of numbers that are the slowest to appear in A109812.
Records in A113233.

Crossrefs

Programs

  • Mathematica
    c[_] = 0; a[1] = c[1] = 1; u = 2; {1}~Join~Reap[Do[k = u; While[Nand[c[k] == 0, BitAnd[a[i - 1], k] == 0], k++]; If[a[i - 1] == u, Sow[i - 1]; While[c[u] > 0, u++]]; Set[{a[i], c[k]}, {k, i}], {i, 2, 1300}]][[-1, -1]]

Extensions

Edited by N. J. A. Sloane, Apr 26 2022

A352575 A109812(n) in binary.

Original entry on oeis.org

1, 10, 100, 11, 1000, 101, 1010, 10000, 110, 1001, 10010, 1100, 10001, 1110, 100000, 111, 11000, 100001, 10100, 1011, 100100, 10011, 101000, 10101, 100010, 1101, 110000, 1111, 1000000, 10110, 101001, 1000010, 11001, 100110, 1000001, 11010, 100101, 1001000, 10111, 1100000, 11011, 1000100, 100011, 11100, 1000011, 101100, 1010000, 100111, 1011000, 10000000
Offset: 1

Views

Author

N. J. A. Sloane, Apr 04 2022

Keywords

Crossrefs

Programs

A352917 Indices k where A109812(k)/k reaches a new high point.

Original entry on oeis.org

1, 3, 5, 8, 15, 29, 40, 50, 108, 164, 649, 651, 5509386, 11271059, 45010096
Offset: 1

Views

Author

David Broadhurst, Aug 17 2022 (entry created by N. J. A. Sloane, Apr 21 2022)

Keywords

Comments

The corresponding values of A109812(k) are given in A352918.
This is a subset of A352204.
The slow growth of A109812(k)/k (see Examples section) suggests that A109812(k)/k is bounded. That is, it appears there is a constant c (between 3.7 and 4) such that A109812(k) < c*k for all k.

Examples

			Let c(k) denote A109812(k). The first 15 record high-points of c(k)/k are as follows:
[c(k)/k, k, c(k), "binary(c(n))"]
[1.000000000, 1, 1, "1"]
[1.333333333, 3, 4, "100"]
[1.600000000, 5, 8, "1000"]
[2.000000000, 8, 16, "10000"]
[2.133333333, 15, 32, "100000"]
[2.206896552, 29, 64, "1000000"]
[2.400000000, 40, 96, "1100000"]
[2.560000000, 50, 128, "10000000"]
[2.962962963, 108, 320, "101000000"]
[3.121951220, 164, 512, "1000000000"]
[3.155624037, 649, 2048, "100000000000"]
[3.539170507, 651, 2304, "100100000000"]
[3.616182275, 5509386, 19922944, "1001100000000000000000000"]
[3.721304271, 11271059, 41943040, "10100000000000000000000000"]
[3.727433952, 45010096, 167772160, "1010000000000000000000000000"]
The values of k and c(k) form the present sequence and A352918.
		

Crossrefs

A113232 A109812(A109812(n)).

Original entry on oeis.org

1, 2, 3, 4, 16, 8, 9, 7, 5, 6, 33, 12, 24, 14, 66, 10, 21, 25, 11, 18, 26, 20, 96, 36, 38, 17, 39, 32, 52, 19, 27, 49, 34, 72, 74, 13, 37, 76, 40, 100, 48, 56, 65, 15, 70, 28, 43, 23, 57, 104, 64, 112, 135, 22, 139, 120, 67, 137, 92, 68, 71, 128, 131, 98, 60, 88, 136, 130, 51
Offset: 1

Views

Author

Reinhard Zumkeller, Oct 19 2005

Keywords

Comments

Inverse integer permutation of A113234;
A113233(a(n)) = a(A113233(n)) = A109812(n).

Crossrefs

Programs

Extensions

Erroneous data corrected by Reinhard Zumkeller, Sep 15 2014

A305372 A109812(2k+1).

Original entry on oeis.org

1, 4, 8, 10, 6, 18, 17, 32, 24, 20, 36, 40, 34, 48, 64, 41, 25, 65, 37, 23, 27, 35, 67, 80, 88, 29, 129, 97, 45, 132, 69, 73, 74, 70, 71, 51, 131, 192, 160, 144, 84, 54, 46, 134, 194, 138, 162, 146, 139, 133, 196, 256, 208, 62, 55, 258, 322, 83, 89, 264, 161, 145, 152, 148, 135, 259, 163, 90, 266, 154, 106, 288
Offset: 0

Views

Author

N. J. A. Sloane, Jun 02 2018

Keywords

Comments

It appears that this is the same as A305369(4k+3)/2.
This is an (apparent) link between A109812 and A305369, and a formula or recurrence would benefit both sequences.

Crossrefs

The graphs of A109812, A252867, A305369, A305372 all have roughly the same, mysterious, fractal-like structure. - N. J. A. Sloane, Jun 03 2018
Showing 1-10 of 82 results. Next