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.

Previous Showing 11-20 of 20 results.

A211967 Triangle of decimal equivalents of binary numbers with no initial repeats, A211027.

Original entry on oeis.org

1, 2, 4, 5, 8, 9, 11, 16, 17, 18, 19, 22, 23, 32, 33, 34, 35, 37, 38, 39, 44, 46, 47, 64, 65, 66, 67, 68, 69, 70, 71, 74, 75, 76, 77, 78, 79, 88, 89, 92, 93, 94, 95, 128, 129, 130, 131, 132, 133, 134, 135, 137, 138, 139, 140, 141, 142, 143, 148, 149, 150
Offset: 1

Views

Author

Omar E. Pol, Nov 30 2012

Keywords

Examples

			Irregular triangle begins:
1;
2;
4,   5;
8,   9, 11;
16, 17, 18, 19, 22, 23;
32, 33, 34, 35, 37, 38, 39, 44, 46, 47;
		

Crossrefs

Columns 1-2 give: A000079(n-1), A000051(n-1) for n>2. Row n has length A093371(n). Right border gives A083329(n-1).

Programs

  • Maple
    s:= proc(n) s(n):= `if`(n=1, [[1]], map(x->
          [[x[], 0], [x[], 1]][], s(n-1))) end:
    T:= proc(n) map (x-> add(x[i]*2^(nops(x)-i), i=1..nops(x)), select
          (proc(l) local i; for i to iquo(nops(l), 2) do if l[1..i]=
          l[i+1..2*i] then return false fi od; true end, s(n)))[] end:
    seq (T(n), n=1..8);  # Alois P. Heinz, Dec 03 2012

A211973 a(n) = A121880(2*n)/2.

Original entry on oeis.org

1, 5, 22, 91, 369, 1486, 5962, 23884, 95607, 382568, 1530552, 6122765, 24492171, 97970902, 391888040, 1567561019, 6270261786, 25081082556, 100324401036, 401297745749, 1605191266193, 6420765631136, 25683063657239, 102732256894319
Offset: 1

Views

Author

Omar E. Pol, Nov 30 2012

Keywords

Crossrefs

Bisection of A093370.

Extensions

More terms from Hakan Icoz, Sep 04 2020

A217211 Number of binary sequences of length n with curling number 2.

Original entry on oeis.org

0, 2, 2, 6, 12, 26, 52, 110, 214, 438, 876, 1762, 3524, 7084, 14144, 28360, 56720, 113542, 227084, 454448, 908804, 1818168, 3636336, 7273614, 14547228, 29096678, 58192994, 116390424, 232780848, 465569860, 931139720, 1862297158, 3724592874, 7449221168, 14898442336, 29796952652, 59593905304
Offset: 1

Views

Author

N. J. A. Sloane, Oct 01 2012

Keywords

Crossrefs

Column 2 of A216955. Cf. A122536, A217212.

Extensions

a(33)-a(37) from Allan Wilks, Oct 06 2012

A218870 Triangle read by rows: T(n,k) = number of aperiodic binary sequences of length n with curling number <= k (1 <= k <= n).

Original entry on oeis.org

2, 2, 2, 4, 6, 6, 6, 10, 12, 12, 12, 24, 28, 30, 30, 20, 40, 48, 52, 54, 54, 40, 92, 112, 120, 124, 126, 126, 74, 174, 210, 226, 234, 238, 240, 240, 148, 362, 438, 474, 490, 498, 502, 504, 504, 286, 700, 860, 928, 960, 976, 984, 988, 990, 990, 572, 1448, 1776, 1916, 1984, 2016, 2032, 2040, 2044, 2046, 2046
Offset: 1

Views

Author

N. J. A. Sloane, Nov 07 2012

Keywords

Comments

S is aperiodic if it is not of the form S = T^m with m > 1.
Rows are partial sums of rows of A218869.
Final entries in rows form A027375. First column is A122536.

Examples

			Triangle begins:
[2]
[2, 2]
[4, 6, 6]
[6, 10, 12, 12]
[12, 24, 28, 30, 30]
[20, 40, 48, 52, 54, 54]
[40, 92, 112, 120, 124, 126, 126]
[74, 174, 210, 226, 234, 238, 240, 240]
[148, 362, 438, 474, 490, 498, 502, 504, 504]
[286, 700, 860, 928, 960, 976, 984, 988, 990, 990]
[572, 1448, 1776, 1916, 1984, 2016, 2032, 2040, 2044, 2046, 2046]
...
		

Crossrefs

A218875 Triangle read by rows: T(n,k) (1 <= k <= n) = number of robust primitive binary sequences of length n and curling number k.

Original entry on oeis.org

2, 2, 0, 4, 2, 0, 6, 4, 2, 0, 10, 12, 4, 2, 0, 20, 20, 8, 4, 2, 0, 36, 52, 20, 8, 4, 2, 0, 72, 98, 36, 16, 8, 4, 2, 0, 142, 214, 76, 36, 16, 8, 4, 2, 0, 280, 414, 160, 68, 32, 16, 8, 4, 2, 0, 560, 870, 326, 140, 68, 32, 16, 8, 4, 2, 0, 1114, 1720, 640, 276, 132, 64, 32, 16, 8, 4, 2, 0
Offset: 1

Views

Author

N. J. A. Sloane, Nov 15 2012

Keywords

Examples

			Triangle begins:
[2],
[2, 0],
[4, 2, 0],
[6, 4, 2, 0],
[10, 12, 4, 2, 0],
[20, 20, 8, 4, 2, 0],
[36, 52, 20, 8, 4, 2, 0],
[72, 98, 36, 16, 8, 4, 2, 0],
[142, 214, 76, 36, 16, 8, 4, 2, 0],
[280, 414, 160, 68, 32, 16, 8, 4, 2, 0],
...
		

Crossrefs

Cf. A216955, A218869, A218876. First column is A216958.

Formula

The triangle in A218869 is the sum of triangles A218875 and A218876.

A211965 Number of binary sequences of length 2n-1 and curling number 1.

Original entry on oeis.org

2, 4, 12, 40, 148, 572, 2248, 8920, 35536, 141860, 566880, 2266400, 9063372, 36249044, 144987304, 579931488, 2319690516, 9278691224, 37114623248, 148458209744, 593832272556, 2375327957436, 9501309564288, 38005233726372, 152020925844036
Offset: 1

Views

Author

Omar E. Pol, Nov 28 2012

Keywords

Comments

Equivalently, number of binary sequences of length 2n-1 with no initial repeats (see A122536).

Crossrefs

Bisection of A122536.

Formula

a(n) = 2*A093371(2n-1).
a(n) = 2*A211966(n-1), n >= 2.

A211966 Number of binary sequences of length 2n and curling number 1.

Original entry on oeis.org

2, 6, 20, 74, 286, 1124, 4460, 17768, 70930, 283440, 1133200, 4531686, 18124522, 72493652, 289965744, 1159845258, 4639345612, 18557311624, 74229104872, 296916136278, 1187663978718, 4750654782144, 19002616863186, 76010462922018
Offset: 1

Views

Author

Omar E. Pol, Nov 28 2012

Keywords

Comments

Equivalently, number of binary sequences of length 2n with no initial repeats (see A122536).

Crossrefs

Bisection of A122536.

Formula

a(n) = 2*A093371(2n) = A093371(2n+1) = A211965(n+1)/2.

A217212 Number of sequences of 2's and 3's of length n with curling number 3.

Original entry on oeis.org

0, 0, 2, 2, 4, 10, 20, 38, 82, 164, 328, 660, 1320, 2640, 5304, 10596, 21192, 42424, 84848, 169668, 339428, 678856, 1357712, 2715548, 5431096, 10862192, 21724746, 43449380, 86898760, 173798220, 347596440, 695192670
Offset: 1

Views

Author

N. J. A. Sloane, Oct 01 2012

Keywords

Crossrefs

Column 3 of A216955. Cf. A122536, A217211.

A218876 Triangle read by rows: T(n,k) (1 <= k <= n) = number of non-robust primitive binary sequences of length n and curling number k.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 6, 2, 0, 0, 0, 0, 0, 0, 0, 0, 10, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

N. J. A. Sloane, Nov 15 2012

Keywords

Examples

			Triangle begins:
[0],
[0, 0],
[0, 0, 0],
[0, 0, 0, 0],
[2, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[4, 0, 0, 0, 0, 0, 0],
[2, 2, 0, 0, 0, 0, 0, 0],
[6, 0, 0, 0, 0, 0, 0, 0, 0],
[6, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[12, 6, 2, 0, 0, 0, 0, 0, 0, 0, 0],
[10, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
...
		

Crossrefs

Formula

The triangle in A218869 is the sum of triangles A218875 and A218876.

A211975 A122536(2n)/2.

Original entry on oeis.org

1, 3, 10, 37, 143, 562, 2230, 8884, 35465, 141720, 566600, 2265843, 9062261, 36246826, 144982872, 579922629, 2319672806, 9278655812, 37114552436, 148458068139, 593831989359, 2375327391072, 9501308431593, 38005231461009, 152020921313377
Offset: 1

Views

Author

Omar E. Pol, Nov 30 2012

Keywords

Crossrefs

Bisection of A093371.
Previous Showing 11-20 of 20 results.