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Search: id:A117974
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| A117974 |
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Triangle where a(1,1)=1; a(n,m) = number of positive integers which are missing from row (n-1) of the triangle, are <= m and are coprime to m. |
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+0
2
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| 1, 0, 0, 1, 1, 2, 0, 0, 0, 1, 0, 0, 1, 1, 3, 0, 0, 1, 0, 2, 1, 0, 0, 0, 1, 2, 1, 4, 0, 0, 0, 1, 1, 1, 3, 3, 0, 0, 1, 0, 2, 1, 4, 2, 5, 0, 0, 0, 1, 1, 0, 2, 2, 2, 3, 0, 0, 0, 0, 1, 1, 3, 2, 4, 2, 7, 0, 0, 0, 0, 0, 1, 2, 1, 2, 1, 5, 2, 0, 0, 0, 1, 2, 0, 3, 2, 3, 3, 7, 2, 9, 0, 0, 0, 0, 1, 1, 3, 1, 3, 0, 5, 2, 7, 3
(list; table; graph; listen)
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OFFSET
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1,6
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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Row 5 of the triangle is [0,0,1,1,3]. There are 0 positive integers which are coprime to 1, are <= 1 and are not among the terms of row 5 (because 1 occurs in row 5). There are 0 positive integers which are <= 2, are coprime to 2 and are not among the terms of row 5. ...(Skipping over the m = 3, 4 and 5 cases.) There is 1 positive integer (5) which is <= 6, is coprime to 6 and does not occur in row 5.
So row 6 is [0,0,1,0,2,1].
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MAPLE
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A117974 := proc(nrow) local a, aprev, anm, m, k ; if nrow = 1 then [1] ; else a := [] ; aprev := A117974(nrow-1) ; for m from 1 to nrow do anm := 0 ; for k from 1 to m do if not k in aprev and gcd(k, m) = 1 then anm := anm+1 ; fi ; od: a := [op(a), anm] ; od; RETURN(a) ; fi ; end: seq(op(A117974(n)), n=1..20) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 05 2007
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CROSSREFS
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Cf. A117975.
Sequence in context: A085981 A127324 A083917 this_sequence A156062 A156064 A158757
Adjacent sequences: A117971 A117972 A117973 this_sequence A117975 A117976 A117977
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KEYWORD
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nonn,tabl
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AUTHOR
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Leroy Quet, Apr 06 2006
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 05 2007
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