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A137371
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a(n) = least semiprime such that all subsets of {a(1),...,a(n)} have a different sum.
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0
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4, 6, 9, 14, 22, 57, 111, 218, 445, 879, 1754, 3518, 7034, 14069, 28129, 56271, 112529, 225073, 450139, 900274, 1800559, 3601109, 7202221, 14404439, 28808881, 57617759, 115235531, 230471069, 460942121
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OFFSET
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1,1
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LINKS
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MAPLE
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isA001358 := proc(n) if numtheory[bigomega](n) = 2 then true; else false; fi ; end: setsum := proc(S) add(i, i=S) ; end: a := [4] : while true do for anxt from op(-1, a)+1 do if isA001358(anxt) then aset := combinat[powerset](convert(a, set) union {anxt} ); sset := {} ; for s in aset do sset := sset union { setsum(s) } ; od: if nops(sset) = nops(aset) then a := [op(a), anxt] ; print(a) ; break ; fi ; fi ; od: od: # R. J. Mathar
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CROSSREFS
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KEYWORD
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more,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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