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Search: id:A066721
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| 1, 8, 18, 50, 60, 81, 98, 105, 128, 242, 264, 308, 338, 416, 495, 520, 546, 560, 578, 625, 663, 675, 684, 864, 935, 952, 1029, 1058, 1083, 1224, 1242, 1254, 1425, 1430, 1682, 1729, 1748, 1771, 1827, 1922, 2436, 2691, 2697, 2720, 2738, 2755, 2790, 2975
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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2*p^2 is in the sequence for all primes except those in A066775.
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LINKS
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David Applegate, First 48186 terms of A066721
David Applegate, C program for computing this sequence
David Applegate, First 48186 terms of A066721 and their factorizations
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MATHEMATICA
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s={1}; xok := Module[ {}, For[ i=1, i<=n, i++, For[ j=1; k=Length[ dl=Divisors[ s[[ i ]]x ]], j<=k, j++; k--, If[ MemberQ[ s, dl[[ j ] ]]&&MemberQ[ s, dl[[ k ] ]], Return[ False ]] ]]; True ]; For[ n=1, True, n++, If[ !PrimeQ[ s[[ n ] ]], Print[ s[[ n ]] ]]; For[ x=s[[ n ]]+1, True, x++, If[ xok, AppendTo[ s, x ]; Break[ ]] ]]
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PROGRAM
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(PARI) {a066721(m) = local(a, rat, n, s, new, b, i, k, j); a=[]; rat=Set([]); n=0; s=0; while(s<m, s++; new=Set([]); b=1; i=1; while(b&&i<=n, k=s/a[i]; if(setsearch(rat, k), b=0, new=setunion(new, Set(k)); k=a[i]/s; if(setsearch(rat, k), b=0, new=setunion(new, Set(k)) )); i++); if(b, rat=setunion(rat, new); a=concat(a, s); n++; if(!isprime(s), print1(s, ", "))))} a066721(3000) (from Klaus Brockhaus, Feb 23 2002)
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CROSSREFS
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Cf. A066720, A066775.
Sequence in context: A034714 A153388 A109988 this_sequence A079704 A133581 A032795
Adjacent sequences: A066718 A066719 A066720 this_sequence A066722 A066723 A066724
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jan 15 2002
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EXTENSIONS
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More terms from Dean Hickerson (dean.hickerson(AT)yahoo.com), Klaus Brockhaus (klaus-brockhaus(AT)t-online.de) and David Applegate (david(AT)research.att.com), Jan 15 2002
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