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.

A087468 Dispersion, read by antidiagonals, of the complement of row 0 of the array R in A087465.

Original entry on oeis.org

1, 3, 2, 7, 5, 4, 12, 10, 8, 6, 19, 16, 14, 11, 9, 27, 24, 21, 18, 15, 13, 37, 33, 30, 26, 23, 20, 17, 48, 44, 40, 36, 32, 29, 25, 22, 61, 56, 52, 47, 43, 39, 35, 31, 28, 75, 70, 65, 60, 55, 51, 46, 42, 38, 34, 91, 85, 80, 74, 69, 64, 59, 54, 50, 45, 41, 108, 102, 96, 90, 84, 79
Offset: 0

Views

Author

Clark Kimberling, Sep 09 2003

Keywords

Comments

The sequence is a permutation of the natural numbers and the array is a transposable dispersion.

Examples

			Northwest corner of R:
1 ... 3 ... 7 ... 12 .. 19
2 ... 5 ... 10 .. 16 .. 24
4 ... 8 ... 14 .. 21 .. 30
6 ... 11 .. 18 .. 26 .. 36
9 ... 15 .. 23 .. 32 .. 43
(See example at A087465.)
		

Crossrefs

Cf. A087465.

Programs

  • Mathematica
    r = 20; r1 = 12;(*r=# rows of T,r1=# rows to show*);
    c = 20; c1 = 12;(*c=# cols of T,c1=# cols to show*);
    s[0] = 1; s[n_] := s[n] = s[n - 1] + 1 + Floor[3 n/2]; u = Table[s[n], {n, 0, 100}]
    v = Complement[Range[Max[u]], u]; f[n_] := v[[n]]; Table[f[n], {n, 1, 30}]
    mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1,   Length[Union[list]]]; rows = {NestList[f, 1, c]}; Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}]; w[i_, j_] := rows[[i, j]]; TableForm[Table[w[j, i], {i, 1, 10}, {j, 1, 10}]]   (*A087468 array*)
    Flatten[Table[w[n - k + 1, k], {n, 1, c1}, {k, 1, n}]] (*A087468 sequence*)
    TableForm[Table[w[j, 1] + w[1, i] + (i - 1)*(j - 1) - 1, {i, 1, 10}, {j, 1, 10}]] (*A087468 array,by formula*)

Formula

Transpose of the array R in A087465.

Extensions

Updated by Clark Kimberling, Sep 23 2014