A309543 Number of odd parts in the partitions of n into 5 parts.

0, 0, 0, 0, 0, 5, 4, 8, 10, 17, 20, 32, 38, 56, 66, 90, 104, 137, 158, 200, 230, 285, 324, 393, 444, 530, 594, 697, 778, 905, 1004, 1153, 1274, 1450, 1594, 1802, 1972, 2213, 2414, 2690, 2924, 3242, 3512, 3873, 4184, 4595, 4948, 5410, 5812, 6330, 6784, 7362

Offset: 0

Author

Wesley Ivan Hurt, Aug 06 2019

Keywords

• nonn
• easy

Examples

			The partitions of n into 5 parts for n = 10, 11, ..
                                                       1+1+1+1+10
                                                        1+1+1+2+9
                                                        1+1+1+3+8
                                                        1+1+1+4+7
                                                        1+1+1+5+6
                                            1+1+1+1+9   1+1+2+2+8
                                            1+1+1+2+8   1+1+2+3+7
                                            1+1+1+3+7   1+1+2+4+6
                                            1+1+1+4+6   1+1+2+5+5
                                            1+1+1+5+5   1+1+3+3+6
                                1+1+1+1+8   1+1+2+2+7   1+1+3+4+5
                                1+1+1+2+7   1+1+2+3+6   1+1+4+4+4
                                1+1+1+3+6   1+1+2+4+5   1+2+2+2+7
                    1+1+1+1+7   1+1+1+4+5   1+1+3+3+5   1+2+2+3+6
                    1+1+1+2+6   1+1+2+2+6   1+1+3+4+4   1+2+2+4+5
                    1+1+1+3+5   1+1+2+3+5   1+2+2+2+6   1+2+3+3+5
        1+1+1+1+6   1+1+1+4+4   1+1+2+4+4   1+2+2+3+5   1+2+3+4+4
        1+1+1+2+5   1+1+2+2+5   1+1+3+3+4   1+2+2+4+4   1+3+3+3+4
        1+1+1+3+4   1+1+2+3+4   1+2+2+2+5   1+2+3+3+4   2+2+2+2+6
        1+1+2+2+4   1+1+3+3+3   1+2+2+3+4   1+3+3+3+3   2+2+2+3+5
        1+1+2+3+3   1+2+2+2+4   1+2+3+3+3   2+2+2+2+5   2+2+2+4+4
        1+2+2+2+3   1+2+2+3+3   2+2+2+2+4   2+2+2+3+4   2+2+3+3+4
        2+2+2+2+2   2+2+2+2+3   2+2+2+3+3   2+2+3+3+3   2+3+3+3+3
--------------------------------------------------------------------------
  n  |     10          11          12          13          14        ...
--------------------------------------------------------------------------
a(n) |     20          32          38          56          66        ...
--------------------------------------------------------------------------
- _Wesley Ivan Hurt_, Sep 12 2019
		

Links

• Index entries for sequences related to partitions

Crossrefs

Cf. A309516.

Programs

Mathematica

Table[Sum[Sum[Sum[Sum[Mod[i, 2] + Mod[j, 2] + Mod[k, 2] + Mod[l, 2] + Mod[n - i - j - k - l, 2], {i, j, Floor[(n - j - k - l)/2]}], {j, k, Floor[(n - k - l)/3]}], {k, l, Floor[(n - l)/4]}], {l, Floor[n/5]}], {n, 0, 50}]

Formula

a(n) = Sum_{l=1..floor(n/5)} Sum_{k=l..floor((n-1)/4)} Sum_{j=k..floor((n-k-l)/3)} Sum_{i=j..floor((n-j-k-l)/2)} ((i mod 2) + (j mod 2) + (k mod 2) + (l mod 2) + ((n-i-j-k-l) mod 2)).

G.f.: -x^5*(2*x^11-x^10+2*x^8+4*x^6-4*x^5+5*x^4-2*x^3+5*x^2-6*x+5) / ((x^2+1) *(x^2+x+1) *(x^2-x+1) *(x^4+x^3+x^2+x+1) *(x^4-x^3+x^2-x+1) *(x^4+1) *(x+1)^3 *(x-1)^5). - Alois P. Heinz, Aug 07 2019