A130048 Complement of inductive sum sequence A130049.

1, 2, 4, 5, 8, 9, 10, 11, 13, 14, 15, 16, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 78, 79, 80, 81, 82, 83, 84, 85

Offset: 1

Author

Clark Kimberling, May 03 2007

Keywords

• nonn

Examples

			(a(1),a(2),...,a(6))=(1,2,4,5,8,9), so x=4 and b(6)=1+2+4+5=12.
(a(1),a(2),...,a(7))=(1,2,4,5,8,9,10), so y=4 and b(7)=5+8+9+10=32.
		

Crossrefs

Cf. A130049, A130050, A130051.

Formula

a(1)=1, a(2)=2, b(1)=0, b(2)=3; for n>=3, let x=Floor(n/2) and y=n-x+1. Then a(n)=least positive integer not among a(1),a(2),...,a(n-1), b(1),b(2),...b(n-1) and b(n)=a(1)+a(2)+...+a(x) if n is even, b(n)=a(y)+a(y+1)+...+a(n) if n is odd.