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.

A144626 Tetrahedron of numbers T(i,j,k) = (i+2*j+3*k)!/(i!*j!*k!*2^j*6^k) read with entries in the order defined in A144625.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 3, 4, 10, 10, 1, 6, 15, 15, 10, 60, 105, 70, 280, 280, 1, 10, 45, 105, 105, 20, 210, 840, 1260, 280, 2520, 6300, 2800, 15400, 15400, 1, 15, 105, 420, 945, 945, 35, 560, 3780, 12600, 17325, 840, 12600, 69300, 138600, 15400, 184800, 600600, 200200, 1401400, 1401400
Offset: 0

Views

Author

N. J. A. Sloane, Jan 18 2009, Jan 19 2009

Keywords

Comments

The slice sums are given by A144416.

Examples

			The n-th slice of the tetrahedrom consists of the terms T(i,j,k) with i+j+k = n.
Slices 0,1,2,3,4,5 are:
....................1
------------------
....................1
...................1.1
------------------
....................10
...................4.10
..................1.3..3
------------------
...................280
..................70.280
................10.60.105
...............1..6.15..15
------------------
..................15400
................2800.15400
...............280.2520.6300
.............20..210.840.1260
............1..10..45..105.105
------------------
.................1401400
.............200200.1401400
.........15400.184800...600600
......840..12600..69300...138600
...35....560....3780....12600...17325
1......15....105....420......945.....945
		

Crossrefs

A144629 Last members of triples listed in A144625.

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 0, 1, 1, 2, 0, 0, 0, 0, 1, 1, 1, 2, 2, 3, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 4, 4, 5, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

N. J. A. Sloane, Jan 18 2009

Keywords

A144627 Initial members of triples listed in A144625.

Original entry on oeis.org

0, 1, 0, 0, 2, 1, 0, 1, 0, 0, 3, 2, 1, 0, 2, 1, 0, 1, 0, 0, 4, 3, 2, 1, 0, 3, 2, 1, 0, 2, 1, 0, 1, 0, 0, 5, 4, 3, 2, 1, 0, 4, 3, 2, 1, 0, 3, 2, 1, 0, 2, 1, 0, 1, 0, 0, 6, 5, 4, 3, 2, 1, 0, 5, 4, 3, 2, 1, 0, 4, 3, 2, 1, 0, 3, 2, 1, 0, 2, 1, 0, 1, 0, 0, 7, 6, 5, 4, 3, 2, 1, 0, 6, 5, 4, 3, 2, 1, 0
Offset: 0

Views

Author

N. J. A. Sloane, Jan 18 2009

Keywords

Programs

  • Maple
    for n from 0 to 7 do
    for k from 0 to n do for j from 0 to n do for i from 0 to n do if i+j+k=n then lprint(i,j,k); fi;
    od: od: od: od:
  • Mathematica
    DeleteCases[Flatten[Table[If[i+j+k==n,i],{n,0,10},{k,0,n},{j,0,n},{i,0,n}]],Null] (* Harvey P. Dale, Mar 27 2012 *)

A144628 Central members of triples listed in A144625.

Original entry on oeis.org

0, 0, 1, 0, 0, 1, 2, 0, 1, 0, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0, 0, 1, 2, 3, 4, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0, 0, 1, 2, 3, 4, 5, 6, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 0, 1, 2, 3, 0, 1, 2, 0, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6
Offset: 0

Views

Author

N. J. A. Sloane, Jan 18 2009

Keywords

A057556 Lexicographic ordering of M x M x M, where M={0,1,2,...}.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 2, 0, 1, 1, 0, 2, 0, 1, 0, 1, 1, 1, 0, 2, 0, 0, 0, 0, 3, 0, 1, 2, 0, 2, 1, 0, 3, 0, 1, 0, 2, 1, 1, 1, 1, 2, 0, 2, 0, 1, 2, 1, 0, 3, 0, 0, 0, 0, 4, 0, 1, 3, 0, 2, 2, 0, 3, 1, 0, 4, 0, 1, 0, 3, 1, 1, 2, 1, 2, 1, 1, 3, 0, 2, 0, 2, 2, 1, 1, 2, 2, 0, 3, 0, 1, 3, 1, 0, 4, 0, 0, 0, 0, 5, 0, 1, 4, 0, 2, 3, 0, 3, 2, 0, 4, 1, 0, 5, 0, 1, 0, 4, 1, 1, 3, 1, 2, 2, 1, 3, 1, 1, 4, 0, 2, 0, 3, 2, 1, 2, 2, 2, 1, 2, 3, 0, 3, 0, 2, 3, 1, 1, 3, 2, 0, 4, 0, 1, 4, 1, 0, 5, 0, 0
Offset: 1

Views

Author

Clark Kimberling, Sep 07 2000

Keywords

Comments

See A057557 for N x N x N, where N={1,2,3,...}.
The triples are sorted first according to their sum, then lexicographically. - Pontus von Brömssen, Aug 16 2023

Examples

			Flatten the list of ordered lattice points, (0,0,0) < (0,0,1) < (0,1,0) < ... to 0,0,0, 0,0,1, 0,1,0, ...
As a three-column array:
  0 0 0
  0 0 1
  0 1 0
  1 0 0
  0 0 2
  0 1 1
  0 2 0
  1 0 1
  1 1 0
  2 0 0
  0 0 3
  0 1 2
  0 2 1
  0 3 0
  1 0 2
  1 1 1
  1 2 0
  2 0 1
  2 1 0
  3 0 0
  ...
		

Crossrefs

Cf. A144625 (each triple reversed).

Programs

  • Mathematica
    lexicographicLattice[{dim_,maxHeight_}]:= Flatten[Array[Sort@Flatten[(Permutations[#1]&)/@IntegerPartitions[#1+dim-1,{dim}],1]&,maxHeight],1]; Flatten@lexicographicLattice[{3,6}]-1
    (* Peter J. C. Moses, Feb 10 2011 *)

Extensions

Extended by Clark Kimberling, Feb 10 2011

A365139 List of free polycubes in binary code (see comments), ordered first by the number of cells, then by the value of the binary code.

Original entry on oeis.org

1, 3, 7, 19, 15, 23, 39, 43, 51, 54, 1043, 31, 47, 55, 59, 87, 118, 173, 179, 182, 199, 230, 1047, 1075, 1078, 2071, 2075, 2149, 2150, 2164, 2214, 2218, 6182, 1049619, 63, 95, 119, 175, 183, 190, 207, 215, 231, 237, 238, 246, 423, 430, 438, 1055, 1079, 1083
Offset: 1

Views

Author

Pontus von Brömssen, Aug 23 2023

Keywords

Comments

The binary code used here is a straight-forward generalization of the binary code in A246521 to d > 2 dimensions. Order the d-tuples of nonnegative integers, first according to their sum, then colexicographically. (For the purposes of this definition, the result will be the same if we use lexicographic order instead.) Label the d-tuples 0, 1, 2, ... in this order. (For d = 3, this is the ordering of triples given by A144625.) Given a d-dimensional polyomino (represented as a finite set of integer d-tuples), consider all the d!*2^d ways of rotating/reflecting it. Translate each such rotation/reflection so that the minimum coordinate is 0 in each dimension, and add the powers of 2 with exponents equal to the labels of the d-tuples of the translation. The binary code of the polyomino (or any finite set of d-tuples) is the minimum of those sums.
Can be read as an irregular triangle, whose n-th row contains A038119(n) terms.

Examples

			Consider the pentacube consisting of a straight tricube with two monocubes attached to two adjacent faces of its middle cube. The following table shows the first few triples (with their ordinal number in front), with those triples appearing in the orientation of the pentacube that minimizes the binary code marked with an "X":
  0. 000 X
  1. 100 X
  2. 010
  3. 001
  4. 200 X
  5. 110 X
  6. 020
  7. 101 X
  8. 011
  9. 002
Consequently, the binary code of this pentacube is 2^0+2^1+2^4+2^5+2^7 = 179 = a(19).
As an irregular triangle:
  1;
  3;
  7, 19;
  15, 23, 39, 43, 51, 54, 1043;
  ...
		

Crossrefs

Cf. A038119, A144625, A246521 (2 dimensions), A365140 (4 dimensions), A365141 (5 dimensions).
Showing 1-6 of 6 results.