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Search: id:A129089
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A129089 a(0)=a(1)=1. a(n) = GCD(a(n-1),n) + GCD(a(n-2),n). +0
2
1, 1, 2, 2, 4, 2, 4, 2, 6, 4, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 6, 4, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 10, 2, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 6, 4, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 10, 2, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 6, 4, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 10, 2, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2, 6, 4, 4, 2, 6, 2, 4, 2, 6, 2, 8, 2 (list; graph; listen)
OFFSET

0,3

COMMENT

a(n) is even for all n >=2.

MAPLE

a[0]:=1: a[1]:=1: for n from 2 to 130 do a[n]:=igcd(a[n-1], n)+igcd(a[n-2], n) od: seq(a[n], n=0..130); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 16 2007

CROSSREFS

Cf. A129088.

Sequence in context: A001223 A118776 A092520 this_sequence A124315 A101113 A055155

Adjacent sequences: A129086 A129087 A129088 this_sequence A129090 A129091 A129092

KEYWORD

nonn

AUTHOR

Leroy Quet (qq-quet(AT)mindspring.com), Mar 29 2007

EXTENSIONS

More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 16 2007

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.


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