A240145 Number of partitions of n into distinct parts, where the difference between the number of odd parts and the number of even parts is 9.

1, 0, 1, 0, 2, 0, 3, 0, 5, 0, 7, 0, 11, 0, 15, 0, 22, 0, 30, 0, 41, 1, 54, 2, 73, 4, 94, 7, 123, 12, 157, 19, 201, 30, 252, 45, 318, 67, 393, 97, 488, 139, 598, 194, 732, 269, 888, 366, 1078, 494, 1296, 658, 1558, 870, 1862, 1137, 2222, 1477, 2639, 1900, 3133

Offset: 81

Author

Alois P. Heinz, Apr 02 2014

Keywords

• nonn

Comments

With offset 90 number of partitions of n into distinct parts, where the difference between the number of odd parts and the number of even parts is -9.

Examples

			a(87) = 3: [23,15,13,11,9,7,5,3,1], [21,17,13,11,9,7,5,3,1], [19,17,15,11,9,7,5,3,1].
a(102) = 1: [19,17,15,13,11,9,7,5,3,2,1].
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 81..1000

Crossrefs

Column k=9 of A240021.

Programs

Maple

b:= proc(n, i, t) option remember; `if`(n>i*(i+1)/2 or
      abs(t)>n, 0, `if`(n=0, 1, b(n, i-1, t)+
      `if`(i>n, 0, b(n-i, i-1, t+(2*irem(i, 2)-1)))))
    end:
a:= n-> b(n$2, -9):
seq(a(n), n=81..145);

Formula

a(n) = [x^n y^9] Product_{i>=1} 1+x^i*y^(2*(i mod 2)-1).