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.

A175595 Square array A(n,t), n>=0, t>=0, read by antidiagonals: A(n,t) is the number of t-core partitions of n.

Original entry on oeis.org

1, 1, 1, 1, 0, 2, 1, 1, 0, 3, 1, 1, 0, 0, 5, 1, 1, 2, 1, 0, 7, 1, 1, 2, 0, 0, 0, 11, 1, 1, 2, 3, 2, 0, 0, 15, 1, 1, 2, 3, 1, 1, 1, 0, 22, 1, 1, 2, 3, 5, 3, 2, 0, 0, 30, 1, 1, 2, 3, 5, 2, 3, 0, 0, 0, 42, 1, 1, 2, 3, 5, 7, 6, 3, 1, 0, 0, 56, 1, 1, 2, 3, 5, 7, 5, 5, 4, 2, 1, 0, 77, 1, 1, 2, 3, 5, 7, 11, 9, 7, 4, 2, 0, 0, 101
Offset: 0

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Author

Alois P. Heinz, Dec 03 2010

Keywords

Comments

A partition of n is a t-core partition if none of the hook numbers associated to the Ferrers-Young diagram is a multiple of t. See Chen reference for definitions.

Examples

			A(4,3) = 2, because there are 2 partitions of 4 such that no hook number is a multiple of 3:
   (1)  2 | 4 1
       +1 | 2
       +1 | 1
   -------+-----
   (2)  3 | 4 2 1
       +1 | 1
Square array A(n,t) begins:
   1,  1,  1,  1,  1,  1,  1,  1,  ...
   1,  0,  1,  1,  1,  1,  1,  1,  ...
   2,  0,  0,  2,  2,  2,  2,  2,  ...
   3,  0,  1,  0,  3,  3,  3,  3,  ...
   5,  0,  0,  2,  1,  5,  5,  5,  ...
   7,  0,  0,  1,  3,  2,  7,  7,  ...
  11,  0,  1,  2,  3,  6,  5, 11,  ...
  15,  0,  0,  0,  3,  5,  9,  8,  ...
		

References

  • Garvan, F. G., A number-theoretic crank associated with open bosonic strings. In Number Theory and Cryptography (Sydney, 1989), 221-226, London Math. Soc. Lecture Note Ser., 154, Cambridge Univ. Press, Cambridge, 1990.
  • James, Gordon; and Kerber, Adalbert, The Representation Theory of the Symmetric Group. Addison-Wesley Publishing Co., Reading, Mass., 1981.

Crossrefs

Rows n=0-1 give A000012, A060576.
Diagonal gives A000094(n+1) for n>0.
Upper diagonal gives A000041.
Lower diagonal (conjectured) gives A086642 for n>0.

Programs

  • Maple
    with(numtheory):
    A:= proc(n, t) option remember; `if`(n=0, 1,
          add(add(`if`(t=0 or irem(d, t)=0, d-d*t, d),
                  d=divisors(j))*A(n-j, t), j=1..n)/n)
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..14);
    (From N. J. A. Sloane, Jun 21 2011: to get M terms of the series for t-core partitions:)
    M:=60;
    f:=proc(t) global M; local q,i,t1;
    t1:=1;
    for i from 1 to M+1 do
    t1:=series(t1*(1-q^(i*t))^t,q,M);
    t1:=series(t1/(1-q^i),q,M);
    od;
    t1;
    end;
    # then for example seriestolist(f(5));
  • Mathematica
    n = 13; f[t_] = (1-x^(t*k))^t/(1-x^k); f[0] = 1/(1-x^k);
    s[t_] := CoefficientList[ Series[ Product[ f[t], {k, 1, n}], {x, 0, n}], x]; m = Table[ PadRight[ s[t], n+1], {t, 0, n}]; Flatten[ Table[ m[[j+1-k, k]], {j, n+1}, {k, j}]] (* Jean-François Alcover, Jul 25 2011, after g.f. *)

Formula

G.f. of column t: Product_{i>=1} (1-x^(t*i))^t/(1-x^i).
Column t is the Euler transform of period t sequence [1, .., 1, 1-t, ..].

Extensions

Additional references from N. J. A. Sloane, Jun 21 2011