A139047 a(0)=a(1)=1. For n >= 2, if a(n-1) is coprime to n, then a(n) = a(n-1) + a(n-2). Otherwise, a(n)=1.

1, 1, 2, 3, 5, 1, 6, 7, 13, 20, 1, 21, 1, 22, 1, 23, 24, 47, 71, 118, 1, 119, 120, 239, 359, 598, 1, 599, 600, 1199, 1799, 2998, 1, 2999, 3000, 1, 3001, 3002, 1, 3003, 3004, 6007, 9011, 15018, 1, 15019, 1, 15020, 1, 15021, 15022, 30043, 1, 30044, 1, 30045, 30046, 60091

Offset

0,3

Links

Jasper Mulder, Table of n, a(n) for n = 0..12500

Example

16 is coprime to a(15) = 23, so a(16) = a(15) + a(14) = 23 + 1 = 24.
20 is not coprime to a(19) = 118, so a(20) = 1.

Crossrefs

Sequence in context: A328145 A096534 A322558 * A343376 A210945 A372112

Adjacent sequences: A139044 A139045 A139046 * A139048 A139049 A139050

Keyword

nonn

Author

Leroy Quet, Jun 01 2008

Extensions

More terms from Jasper Mulder (jasper.mulder(AT)planet.nl), Oct 12 2009

Status

approved