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Search: id:A072284
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| A072284 |
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n begins a new chain of square-free integers. I.e. n is square-free but n-1 is not. |
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+0
5
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| 1, 5, 10, 13, 17, 19, 21, 26, 29, 33, 37, 41, 46, 51, 53, 55, 57, 61, 65, 69, 73, 77, 82, 85, 89, 91, 93, 97, 101, 105, 109, 113, 118, 122, 127, 129, 133, 137, 141, 145, 149, 151, 154, 157, 161, 163, 165, 170, 173, 177, 181, 185, 190, 193, 197, 199, 201, 205, 209
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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A136742 mod a(n) = 0; A136742(n)=PRODUCT(a(n)+k:0<=k<A120992(n)); A136743(n)=SUM(A001221(a(n)+k):0<=k<A120992(n)). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jan 20 2008
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LINKS
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R. Zumkeller, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Squarefree
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EXAMPLE
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1 begins a new chain 1, 2, 3 of square-free integers. 4 is not square-free. Then 5 begins a new chain 5, 6, 7 of square-free integers. Hence 1 and 5 are terms of the sequence.
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PROGRAM
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(PARI) n=1:for(k=1, 100, while(!issquarefree(n), n=n+1):print1(n", "):while(issquarefree(n), n=n+1))
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CROSSREFS
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Cf. A005117.
Sequence in context: A084645 A092604 A050127 this_sequence A024507 A004431 A025302
Adjacent sequences: A072281 A072282 A072283 this_sequence A072285 A072286 A072287
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KEYWORD
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easy,nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jul 10 2002
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EXTENSIONS
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More terms from Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 19 2003
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