0,1

a(1) = -1 since 6 = 2*3 and 3 = 2*2 - 1.

a(4) = +1 since 21 = 3*7 and 7 = 2*3 + 1.

Cf. A068443.

Sequence in context: A015156 A016303 A053981 this_sequence A016266 A016192 A015970

Adjacent sequences: A119661 A119662 A119663 this_sequence A119665 A119666 A119667

sign

Greg Huber (huber(AT)alum.mit.edu), Jul 28 2006