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Search: id:A117213
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| A117213 |
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a(n) = smallest term of sequence A002110 divisible by n-th squarefree positive integer. |
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+0
2
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| 1, 2, 6, 30, 6, 210, 30, 2310, 30030, 210, 30, 510510, 9699690, 210, 2310, 223092870, 30030, 6469693230, 30, 200560490130, 2310, 510510, 210, 7420738134810, 9699690, 30030, 304250263527210, 210, 13082761331670030, 223092870
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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FORMULA
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For n >= 2, a(n) = product of the primes <= A073482(n).
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EXAMPLE
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10 is the 7th squarefree integer. And 2*3*5 = 30 is the smallest primorial number divisible by 10 = 2*5. So a(7) = 30.
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MAPLE
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issquarefree := proc(n::integer) local nf, ifa, lar ; nf := op(2, ifactors(n)) ; for ifa from 1 to nops(nf) do lar := op(1, op(ifa, nf)) ; if op(2, op(ifa, nf)) >= 2 then RETURN(0) ; fi ; od : RETURN(lar) ; end: primor := proc(n::integer) local resul, nepr ; resul :=2 ; nepr :=3 ; while nepr <= n do resul := resul*nepr ; nepr:=nextprime(nepr) ; od : RETURN(resul) ; end: printf("1, ") ; for n from 2 to 100 do lfa := issquarefree(n) ; if lfa > 0 then printf("%a, ", primor(lfa) ) ; fi ; od : - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 02 2006
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CROSSREFS
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Cf. A002110, A073482, A117214.
Sequence in context: A076978 A079615 A074168 this_sequence A127797 A077634 A095198
Adjacent sequences: A117210 A117211 A117212 this_sequence A117214 A117215 A117216
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Mar 03 2006
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 02 2006
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