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.

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A322763 Irregular triangle read by rows: to get row n, take partitions of n ordered as in A080577, and in each partition, change each j-th occurrence of k to j; use uncompressed notation as in A080577.

Original entry on oeis.org

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

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Author

N. J. A. Sloane, Dec 30 2018

Keywords

Comments

The compressed form seems easier to understand. This is A322762 but with each partition, after it has been transformed, written as the string of its parts.

Examples

			In compressed form (see A322762) triangle begins:
  1,
  1, 12,
  1, 11, 123,
  1, 11, 12, 112, 1234,
  1, 11, 11, 112, 121, 1123, 12345,
  1, 11, 11, 112, 12, 111, 1123, 123, 1212, 11234, 123456,
  ...
For example, the 11 partitions of 6 are:
6, 51, 42, 411, 33, 321, 3111, 222, 2211, 21111, 111111,
and applying the transformation we get:
1, 11, 11, 112, 12, 111, 1123, 123, 1212, 11234, 123456.
In the uncompressed notation the triangle begins:
  {1},
  {1}, {1,2},
  {1}, {1,1}, {1,2,3},
  {1}, {1,1}, {1,2}, {1,1,2}, {1,2,3,4},
  {1}, {1,1}, {1,1}, {1,1,2}, {1,2,1}, {1,1,2,3}, {1,2,3,4,5},
  ...
		

References

  • D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.2.1.5, Problem 73, pp. 415, 761.

Crossrefs

Programs

  • Maple
    b:= (n, i)-> `if`(n=0 or i=1, [[$1..n]], [(t->
        seq(map(x-> [$1..(t+1-j), x[]], b(n-i*(t+1-j)
        , i-1))[], j=1..t))(iquo(n, i)), b(n, i-1)[]]):
    T:= n-> map(x-> x[], b(n$2))[]:
    seq(T(n), n=1..10);  # Alois P. Heinz, Dec 30 2018

Extensions

More terms from Alois P. Heinz, Dec 30 2018
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