Search: id:A072284
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%I A072284
%S A072284 1,5,10,13,17,19,21,26,29,33,37,41,46,51,53,55,57,61,65,69,73,77,82,85,
%T A072284 89,91,93,97,101,105,109,113,118,122,127,129,133,137,141,145,149,151,
%U A072284 154,157,161,163,165,170,173,177,181,185,190,193,197,199,201,205,209
%N A072284 n begins a new chain of square-free integers. I.e. n is square-free but 
               n-1 is not.
%C A072284 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
%H A072284 R. Zumkeller, <a href="b072284.txt">Table of n, a(n) for n = 1..1000</
               a>
%H A072284 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Squarefree.html">Squarefree</a>
%e A072284 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.
%o A072284 (PARI) n=1:for(k=1,100, while(!issquarefree(n),n=n+1):print1(n","):while(issquarefree(n),
               n=n+1))
%Y A072284 Cf. A005117.
%Y A072284 Sequence in context: A084645 A092604 A050127 this_sequence A024507 A004431 
               A025302
%Y A072284 Adjacent sequences: A072281 A072282 A072283 this_sequence A072285 A072286 
               A072287
%K A072284 easy,nonn
%O A072284 1,2
%A A072284 Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jul 10 2002
%E A072284 More terms from Ralf Stephan (ralf(AT)ark.in-berlin.de), Mar 19 2003

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