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Search: id:A078637
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| A078637 |
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rad{n(n+1)(n+2)}, where rad(m) = largest square-free number dividing m (see A007947). |
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+0
1
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| 6, 6, 30, 30, 210, 42, 42, 30, 330, 330, 858, 546, 2730, 210, 510, 102, 1938, 570, 3990, 2310, 10626, 1518, 690, 390, 390, 546, 1218, 6090, 26970, 930, 2046, 1122, 39270, 3570, 7770, 4218, 54834, 7410, 15990, 8610, 74046, 19866, 14190, 7590, 32430, 6486
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = rad(n)*rad(n+1)*rad(n+2) if n odd; or rad(n/2)*rad(n+1)*rad(n/2+1) if n even - C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 13 2004
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EXAMPLE
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a(3)=rad(3.4.5)=30
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MAPLE
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with(numtheory):rad:=proc(n) local s, i: s:=ifactors(n)[2]: RETURN(mul(s[i][1], i=1..nops(s))): end; seq(rad(n*(n+1)*(n+2)), n=1..60); seq(piecewise(n mod 2=0, rad(n/2)*rad(n+1)*rad(n/2+1), rad(n)*rad(n+1)*rad(n+2)), n=1..60); (C. Ronaldo)
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PROGRAM
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(PARI) rad(n)=local(p, i); p=factor(n)[, 1]; prod(i=1, length(p), p[i]) for (k=1, 100, print1(rad(k*(k+1)*(k+2))", "))
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CROSSREFS
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Cf. A007947.
Sequence in context: A066714 A054436 A055522 this_sequence A071021 A074002 A015699
Adjacent sequences: A078634 A078635 A078636 this_sequence A078638 A078639 A078640
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KEYWORD
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nonn
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Dec 12 2002
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