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A113605
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a(1) = a(2) = a(3) = 1; a(n) = a(n-3) + GCD(a(n-1),a(n-2)).
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2
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1, 1, 1, 2, 2, 3, 3, 5, 4, 4, 9, 5, 5, 14, 6, 7, 15, 7, 8, 16, 15, 9, 19, 16, 10, 21, 17, 11, 22, 28, 13, 23, 29, 14, 24, 31, 15, 25, 36, 16, 29, 37, 17, 30, 38, 19, 49, 39, 20, 50, 49, 21, 57, 52, 22, 59, 53, 23, 60, 54, 29, 61, 55, 30, 66, 61, 31, 67, 62, 32, 69, 63, 35, 76, 64
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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EXAMPLE
| a(16) = a(13) + GCD(a(15),a(14)) = 5 + GCD(6,14) = 7.
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MAPLE
| a[1]:=1: a[2]:=1: a[3]:=1: for n from 4 to 100 do a[n]:=a[n-3]+gcd(a[n-1], a[n-2]) od: seq(a[n], n=1..90); (Deutsch)
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MATHEMATICA
| a[1] = a[2] = a[3] = 1; a[n_] := a[n] = a[n - 3] + GCD[a[n - 1], a[n - 2]]; Array[a, 75] (* Robert G. Wilson v *)
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CROSSREFS
| Sequence in context: A069974 A039650 A039649 * A070230 A007150 A122352
Adjacent sequences: A113602 A113603 A113604 * A113606 A113607 A113608
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Jan 26 2006
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(at)rgwv.com) and Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 01 2006
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