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Search: id:A122089
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| A122089 |
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a(1)=a(2)=1. a(n) = smallest integer which is greater than a(n-1) and is coprime to (a(n-1)+a(n-2)). |
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+0
1
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| 1, 1, 3, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 37, 39, 41, 43, 47, 49, 53, 55, 59, 61, 67, 69, 71, 73, 77, 79, 83, 85, 89, 91, 97, 99, 101, 103, 107, 109, 113, 115, 119, 121, 127, 129, 131, 133, 137, 139, 143, 145, 149, 151, 157, 159, 161, 163, 167, 169, 173, 175, 179
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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a(9) +a(10) = 42. The smallest integer greater than a(10)=23 which is coprime to 42 is 25. So a(11) = 25.
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MAPLE
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A122089 := proc(maxn) local a, nexta, n ; a := [1, 1] ; for n from 3 to maxn do nexta := op(n-1, a)+1 ; while gcd(nexta, op(n-2, a)+op(n-1, a)) >1 do nexta := nexta+1 ; od ; a := [op(a), nexta] ; od ; RETURN(a) ; end: maxn := 100 : alist := A122089(maxn) : for i from 1 to maxn do printf("%d, ", op(i, alist)) ; end : - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 21 2006
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MATHEMATICA
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f[l_List] := Block[{k = l[[ -1]] + 1}, While[GCD[k, l[[ -1]] + l[[ -2]]] > 1, k++ ]; Append[l, k]]; Nest[f, {1, 1}, 61] (*Chandler*)
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CROSSREFS
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Sequence in context: A081118 A003255 A118749 this_sequence A109860 A100392 A067019
Adjacent sequences: A122086 A122087 A122088 this_sequence A122090 A122091 A122092
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Oct 17 2006
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Oct 19 2006
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 21 2006
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