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A297351
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Smallest number k such that, for any set S of k distinct nonzero residues mod p = prime(n), any residue mod p can be represented as a sum of zero or more distinct elements of S.
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0
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1, 2, 3, 4, 6, 6, 7, 8, 9, 10, 10, 11, 12, 12, 13, 14, 15, 15, 16, 16, 16, 17
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OFFSET
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1,2
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LINKS
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FORMULA
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For p = prime(n) > 3, sqrt(4p + 5) - 2 < a(n) <= sqrt(4p). The former bound is due to Erdős & Heilbronn and the latter to Olson.
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PROG
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(PARI) sumHitsAll(v, m)=my(u=[0], n); for(i=1, #v, n=v[i]; u=Set(concat(u, apply(j->(j+n)%m, u))); if(#u==m, return(1))); 0
a(n, p=prime(n))=for(s=sqrtint(4*p+2)-1, sqrtint(4*p)-1, forvec(v=vector(s, i, [1, p-1]), if(!sumHitsAll(v, p), next(2)), 2); return(s)); sqrtint(4*p)
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CROSSREFS
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KEYWORD
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hard,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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