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A144294
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Let k = n-th nonsquare = A000037(n); then a(n) = smallest prime p such that k is not a square mod p.
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4
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3, 5, 3, 7, 5, 3, 7, 3, 5, 5, 3, 13, 3, 5, 7, 3, 11, 5, 3, 7, 3, 5, 5, 3, 11, 7, 3, 5, 7, 3, 5, 3, 11, 7, 3, 5, 5, 3, 7, 11, 3, 5, 3, 11, 5, 3, 7, 7, 3, 5, 5, 3, 13, 7, 3, 5, 3, 7, 5, 3, 7, 13, 3, 5, 5, 3, 7, 7, 3, 5, 11, 3, 5, 3, 11, 11, 3, 5, 5, 3, 7, 17, 3, 5, 7, 3, 7, 5, 3, 13
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| In a posting to the Number Theory List, Oct 15 2008, Kurt Foster remarks that a positive integer M is a square iff M is a quadratic residue mod p for every prime p which does not divide M. He then asks how fast the present sequence grows.
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MAPLE
| with(numtheory); f:=proc(n) local M, i, j, k; M:=100000; for i from 2 to M do if legendre(n, ithprime(i)) = -1 then RETURN(ithprime(i)); fi; od; -1; end;
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CROSSREFS
| For records see A144295, A144296. See A092419 for another version.
Sequence in context: A075572 A089992 A074593 * A154800 A137768 A137769
Adjacent sequences: A144291 A144292 A144293 * A144295 A144296 A144297
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Dec 03 2008
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