A330888 Irregular triangle read by rows: T(n,k) is the number of parts in the partition of n into k consecutive parts that differ by 3, n >= 1, k >= 1, and the first element of column k is in the row that is the k-th pentagonal number (A000326).

1, 1, 1, 1, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 0, 3, 1, 2, 0, 1, 0, 0, 1, 2, 3, 1, 0, 0, 1, 2, 0, 1, 0, 3, 1, 2, 0, 1, 0, 0, 1, 2, 3, 1, 0, 0, 4, 1, 2, 0, 0, 1, 0, 3, 0, 1, 2, 0, 0, 1, 0, 0, 4, 1, 2, 3, 0, 1, 0, 0, 0, 1, 2, 0, 0, 1, 0, 3, 4, 1, 2, 0, 0, 1, 0, 0, 0, 1, 2, 3, 0, 1, 0, 0, 4, 1, 2, 0, 0, 5

Offset: 1

Author

Omar E. Pol, Apr 30 2020

Keywords

• nonn
• tabf

Comments

Since the trivial partition n is counted, so T(n,1) = 1.

This is an irregular triangle read by rows: T(n,k), n >= 1, k >= 1, in which column k lists k's interleaved with k-1 zeros, and the first element of column k is in the row that is the k-th pentagonal number.

Examples

			Triangle begins (rows 1..26):
1;
1;
1;
1;
1, 2;
1, 0;
1, 2;
1, 0;
1, 2;
1, 0;
1, 2;
1, 0, 3;
1, 2, 0;
1, 0, 0;
1, 2, 3;
1, 0, 0;
1, 2, 0;
1, 0, 3;
1, 2, 0;
1, 0, 0;
1, 2, 3;
1, 0, 0, 4;
1, 2, 0, 0;
1, 0, 3, 0;
1, 2, 0, 0;
1, 0, 0, 4;
...
For n = 21 there are three partitions of 21 into consecutive parts that differ by 3, including 21 as a partition. They are [21], [12, 9] and [10, 7, 4]. The number of parts of these partitions are 1, 2 and 3 respectively, so the 21st row of the triangle is [1, 2, 3].
		

Crossrefs

Cf. A000326, A330887.

Other triangles of the same family are A127093, A285914, A330466.

Programs

Maple

A330888 := proc(n,k)
    k*A330887(n,k) ;
end proc:
for n from 1 to 40 do
    for k from 1 do
        if n>= A000325(k) then
            printf("%d,",A330888(n,k)) ;
        else
            break;
        end if;
    end do:
    printf("\n") ;
end do: # R. J. Mathar, Oct 02 2020

Formula

T(n,k) = k*A330887(n,k).