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 1-6 of 6 results.

A182621 a(n) is the concatenation of the binary numbers that are the divisors of n written in base 2.

Original entry on oeis.org

1, 110, 111, 110100, 1101, 11011110, 1111, 1101001000, 1111001, 1101011010, 11011, 110111001101100, 11101, 1101111110, 1111011111, 110100100010000, 110001, 11011110100110010, 110011, 110100101101010100, 11111110101, 110101110110, 110111, 110111001101000110011000
Offset: 1

Views

Author

Omar E. Pol, Nov 22 2010

Keywords

Comments

a(n) is the concatenation of the numbers of row n of triangle A182620. The first repeated element is a(15) = 1111011111 = a(479), where a(15) is the concatenation of 1, 11, 101 and 1111 but a(479) is the concatenation of 1 and 111011111. See A182620 and A182622 for more information.

Examples

			The divisors of 10 are 1, 2, 5, 10, which written in base 2 are 1, 10, 101, 1010. The concatenation of 1, 10, 101, 1010 is 1101011010, so a(10) = 1101011010.
		

Crossrefs

Programs

  • Mathematica
    A182621[n_]:=FromDigits[Flatten[IntegerDigits[Divisors[n],2]]];Array[A182621,50] (* Paolo Xausa, Aug 31 2023 *)
  • PARI
    a(n) = fromdigits(concat(apply(binary,divisors(n)))); \\ Kevin Ryde, May 02 2023
  • Python
    from sympy import divisors
    def a(n): return int("".join(bin(d)[2:] for d in divisors(n)))
    print([a(n) for n in range(1, 25)]) # Michael S. Branicky, Apr 20 2022
    
  • Sage
    A182621 = lambda n: Integer(''.join(d.str(base=2) for d in divisors(n))) # D. S. McNeil, Dec 19 2010
    

A182630 T(n,k) = A002024(k+1)*n + A002262(k), n >= 0, k >= 0, read by antidiagonals.

Original entry on oeis.org

0, 1, 0, 2, 2, 1, 3, 4, 3, 0, 4, 6, 5, 3, 1, 5, 8, 7, 6, 4, 2, 6, 10, 9, 9, 7, 5, 0, 7, 12, 11, 12, 10, 8, 4, 1, 8, 14, 13, 15, 13, 11, 8, 5, 2, 9, 16, 15, 18, 16, 14, 12, 9, 6, 3, 10, 18, 17, 21, 19, 17, 16, 13, 10, 7, 0
Offset: 0

Views

Author

Omar E. Pol, Dec 06 2010

Keywords

Comments

A table of congruences.
See A182631 for another version.

Examples

			Table of congruences:
===============+====+=======+==========+=============+====
           mod |  1 |   2   |     3    |      4      | ...
===============+====+=======+==========+=============+====
  congruent to |  0 |  0  1 |  0  1  2 |  0  1  2  3 | ...
===============+====+=======+==========+=============+====
Array begins:  |  0 |  0  1 |  0  1  2 |  0  1  2  3 | ...
               |  1 |  2  3 |  3  4  5 |  4  5  6  7 | ...
               |  2 |  4  5 |  6  7  8 |  8  9 10 11 | ...
               |  3 |  6  7 |  9 10 11 | 12 13 14 15 | ...
               |  4 |  8  9 | 12 13 14 | 16 17 18 19 | ...
               |  5 | 10 11 | 15 16 17 | 20 21 22 23 | ...
               |  6 | 12 13 | 18 19 20 | 24 25 26 27 | ...
               |  7 | 14 15 | 21 22 23 | 28 29 30 31 | ...
               |  8 | 16 17 | 24 25 26 | 32 33 34 35 | ...
               |  9 | 18 19 | 27 28 29 | 36 37 38 39 | ...
               | 10 | 20 21 | 30 31 32 | 40 41 42 43 | ...
		

Crossrefs

Programs

A182814 Main diagonal of table A182630.

Original entry on oeis.org

0, 2, 5, 9, 13, 17, 24, 29, 34, 39, 50, 56, 62, 68, 74, 90, 97, 104, 111, 118, 125, 147, 155, 163, 171, 179, 187, 195, 224, 233, 242, 251, 260, 269, 278, 287, 324, 334, 344, 354, 364, 374, 384, 394, 404, 450, 461, 472, 483, 494, 505, 516, 527, 538, 549, 605, 617, 629, 641, 653, 665, 677, 689, 701, 713, 725, 792, 805, 818, 831, 844, 857, 870, 883, 896, 909, 922, 935, 1014
Offset: 0

Views

Author

Omar E. Pol, Dec 06 2010

Keywords

Comments

Main diagonal of a table of congruences.

Crossrefs

Programs

Formula

a(n) = A182630(n,n).

A182810 Array read by antidiagonals which lists the partition number of the numbers of the table A182630.

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 3, 5, 3, 1, 5, 11, 7, 3, 1, 7, 22, 15, 11, 5, 2, 11, 42, 30, 30, 15, 7, 1, 15, 77, 56, 77, 42, 22, 5, 1, 22, 135, 101, 176, 101, 56, 22, 7, 2, 30, 231, 176, 385, 231, 135, 77, 30, 11, 3, 42, 385, 297, 792, 490, 297, 231, 101, 42, 15, 1
Offset: 0

Views

Author

Omar E. Pol, Dec 06 2010

Keywords

Examples

			...1....1....1....1....1....2....1....1....2....3....1.
...1....2....3....3....5....7....5....7...11...15....7.
...2....5....7...11...15...22...22...30...42...56...42.
...3...11...15...30...42...56...77..101..135..176..176.
...5...22...30...77..101..135..231..297..385..490..627.
...7...42...56..176..231..297..627..792.1002.1255.1958.
		

Crossrefs

Programs

  • Maple
    A182810 := proc(n,k) combinat[numbpart](A182630(n,k)) ; end proc:

Formula

T(n,k) = A000041(A182630(n,k)), n,k >=0.

A182815 The third row of table A182630.

Original entry on oeis.org

2, 4, 5, 6, 7, 8, 8, 9, 10, 11, 10, 11, 12, 13, 14, 12, 13, 14, 15, 16, 17, 14, 15, 16, 17, 18, 19, 20, 16, 17, 18, 19, 20, 21, 22, 23, 18, 19, 20, 21, 22, 23, 24, 25, 26, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 26
Offset: 0

Views

Author

Omar E. Pol, Dec 06 2010

Keywords

Crossrefs

Programs

  • Maple
    seq(A182630(2,n),n=0..80) ;

Formula

a(n) = A182630(2,n).

A182692 Composite Beatty sequence of sqrt(3).

Original entry on oeis.org

2, 3, 7, 12, 28, 48, 113, 195, 461, 798, 1888, 3270, 7736, 13399, 31702, 54909, 129916, 225021, 532405, 922152, 2181835, 3779049, 8941325, 15486829, 36642230, 63466204, 150162650, 260089339, 615377983, 1065865932
Offset: 1

Views

Author

Clark Kimberling, Nov 27 2010

Keywords

Comments

The bisection (3,12,48,...) is a subsequence of A022838.
The bisection (2,7,28,...) is a subsequence of A054406.
See the comment at A107857 regarding Beatty sequences.

Crossrefs

Formula

a(n)=floor(s*a(n-1)) if n odd, a(n)=floor(r*a(n-1)) if n even, where r=sqrt(3), s=(r+3)/2, a(1)=floor(s).
Showing 1-6 of 6 results.