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.

A183170 First of two trees generated by the Beatty sequence of sqrt(2).

Original entry on oeis.org

1, 3, 4, 10, 5, 13, 14, 34, 7, 17, 18, 44, 19, 47, 48, 116, 9, 23, 24, 58, 25, 61, 62, 150, 26, 64, 66, 160, 67, 163, 164, 396, 12, 30, 32, 78, 33, 81, 82, 198, 35, 85, 86, 208, 87, 211, 212, 512, 36, 88, 90, 218, 93, 225, 226, 546, 94, 228
Offset: 1

Views

Author

Clark Kimberling, Dec 28 2010

Keywords

Comments

This tree grows from (L(1),U(1))=(1,3). The other tree, A183171, grows from (L(2),U(2))=(2,6). Here, L is the Beatty sequence A001951 of r=sqrt(2); U is the Beatty sequence A001952 of s=r/(r-1). The two trees are complementary; that is, every positive integer is in exactly one tree. (L and U are complementary, too.) The sequence formed by taking the terms of this tree in increasing order is A183172.

Examples

			First levels of the tree:
.......................1
.......................3
..............4...................10
.........5..........13........14........34
.......7..17......18..44....19..47....48..116
		

Crossrefs

Programs

  • Mathematica
    a = {1, 3}; row = {a[[-1]]}; r = Sqrt[2]; s = r/(r - 1); Do[a = Join[a, row = Flatten[{Floor[#*{r, s}]} & /@ row]], {n, 5}]; a (* Ivan Neretin, May 25 2015 *)

Formula

See the formula at A178528, but use r=sqrt(2) instead of r=sqrt(3).

A183211 First of two trees generated by floor[(3n-1)/2].

Original entry on oeis.org

1, 3, 4, 9, 5, 12, 13, 27, 7, 15, 17, 36, 19, 39, 40, 81, 10, 21, 22, 45, 25, 51, 53, 108, 28, 57, 58, 117, 59, 120, 121, 243, 14, 30, 31, 63, 32, 66, 67, 135, 37, 75, 76, 153, 79, 159, 161, 324, 41, 84, 85, 171, 86, 174, 175, 351, 88, 177
Offset: 1

Views

Author

Clark Kimberling, Dec 30 2010

Keywords

Comments

This tree grows from (L(1),U(1))=(1,3). The second tree, A183212, grows from (L(2),U(2))=(2,6). Here, L(n)=floor[(3n-1)/2] and U(n)=3n. The two trees are complementary in the sense that every positive integer is in exactly one tree. The sequence formed by taking the terms of this tree in increasing order is A183213. Leftmost branch of this tree: A183207. Rightmost: A000244. See A183170 and A183171 for the two trees generated by the Beatty sequence of sqrt(2).

Examples

			First four levels of the tree:
.......................1
.......................3
..............4..................9
............5...12............13....27
		

Crossrefs

Programs

  • Mathematica
    a = {1, 3}; row = {a[[-1]]}; Do[a = Join[a, row = Flatten[{Quotient[3 # - 1, 2], 3 #} & /@ row]], {n, 5}]; a (* Ivan Neretin, May 25 2015 *)

Formula

See the formula at A183209, but use L(n)=floor[(3n-1)/2] and U(n)=3n instead of L(n)=floor(3n/2) and U(n)=3n-1.

A183172 Ordering of the numbers in set S generated by these rules: 1 is in S, and if n is in S then floor(r*n) and floor(s*n) are in S, where r=sqrt(2) and s=r/(r-1).

Original entry on oeis.org

1, 3, 4, 5, 7, 9, 10, 12, 13, 14, 16, 17, 18, 19, 22, 23, 24, 25, 26, 30, 31, 32, 33, 34, 35, 36, 40, 42, 43, 44, 45, 46, 47, 48, 49, 50, 54, 56, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 75, 76, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 93
Offset: 1

Views

Author

Clark Kimberling, Dec 28 2010

Keywords

Comments

The sequence results from flattening and sorting the tree at A183170. Complement of A183173, obtained from the tree at A183171.

Crossrefs

Programs

  • Mathematica
    nn=100; t={1}; r=Sqrt[2]; s=r/(r-1); t0=t; While[t=Select[Union[t, Floor[r*t], Floor[s*t]], #<=nn&]; t0 != t, t0=t]; t

Formula

See A183170.

A183173 Ordering of the numbers in set S generated by these rules: 2 is in S, and if n is in S then floor(r*n) and floor(s*n) are in S, where r=sqrt(2) and s=r/(r-1).

Original entry on oeis.org

2, 6, 8, 11, 15, 20, 21, 27, 28, 29, 37, 38, 39, 41, 51, 52, 53, 55, 57, 68, 71, 72, 73, 74, 77, 80, 92, 95, 96, 99, 100, 101, 103, 104, 108, 113, 126, 129, 130, 133, 134, 135, 139, 140, 141, 142, 145, 147, 152, 159, 174, 177, 178, 180, 182
Offset: 1

Views

Author

Clark Kimberling, Dec 29 2010

Keywords

Comments

The sequence results from flattening and sorting the tree at A183171. Complement of A183172, obtained from the tree at A183170.

Crossrefs

Programs

  • Mathematica
    nn=200; t={2}; r=Sqrt[2]; s=r/(r-1); t0=t; While[t=Select[Union[t, Floor[r*t], Floor[s*t]], # <= nn &]; t0 != t, t0=t]; t

Formula

Extensions

Missing term 113 inserted by John W. Layman, Dec 29 2010
Showing 1-4 of 4 results.