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A236454
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Smallest number not dividing n^2.
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5
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2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2
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OFFSET
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1,1
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COMMENTS
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Differs from A053669, "smallest prime not dividing n", for the first time at n=210, where a(210)=8, while A053669(210)=11. A235921 lists all n for which a(n) differs from A053669(n).
Differs from A214720 at n=2, 210, 630, 1050, 1470, 1890, 2310,.... - R. J. Mathar, Mar 30 2014
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LINKS
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Antti Karttunen, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n) = A007978(A000290(n)) = A007978(n^2).
a(n) = A235918(n)+1.
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MAPLE
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A236454 := proc(n)
for m from 2 do
if modp(n^2, m) <> 0 then
return m;
end if;
end do:
end proc:# R. J. Mathar, Mar 30 2014
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MATHEMATICA
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Join[{2, 3}, Table[Complement[Range[n], Divisors[n^2]][[1]], {n, 3, 90}]] (* Harvey P. Dale, Mar 18 2018 *)
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PROG
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(Scheme) (define (A236454 n) (A007978 (A000290 n)))
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CROSSREFS
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One more than A235918.
Cf. also A000290, A007978, A053669, A235921.
Sequence in context: A087242 A123556 A284017 * A053669 A342309 A112047
Adjacent sequences: A236451 A236452 A236453 * A236455 A236456 A236457
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KEYWORD
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nonn
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AUTHOR
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Antti Karttunen, Jan 26 2014
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STATUS
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approved
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