A010737 a(n) = 2*a(n-2) + 1.

4, 6, 9, 13, 19, 27, 39, 55, 79, 111, 159, 223, 319, 447, 639, 895, 1279, 1791, 2559, 3583, 5119, 7167, 10239, 14335, 20479, 28671, 40959, 57343, 81919, 114687, 163839, 229375, 327679, 458751, 655359

Offset: 0

Author

N. J. A. Sloane, Ulrich Hund (hund(AT)math.tu-berlin.de)

Keywords

• nonn
• easy

Programs

Maple

A010737 := proc(n) options remember; if n <= 1 then 2*n+4 else 2*A010737(n-2)+1; fi end;

PARI

a(n)=(6-(-1)^n)*2^floor(n/2)-1

Formula

a(2n)=5*2^n-1 and a(2n+1)=7*2^n-1 or a(n)=(6-(-1)^n)*2^floor(n/2)-1 - Benoit Cloitre, May 04 2003