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A113646
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a(n) is the smallest composite integer which is >= n.
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7
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4, 4, 4, 4, 6, 6, 8, 8, 9, 10, 12, 12, 14, 14, 15, 16, 18, 18, 20, 20, 21, 22, 24, 24, 25, 26, 27, 28, 30, 30, 32, 32, 33, 34, 35, 36, 38, 38, 39, 40, 42, 42, 44, 44, 45, 46, 48, 48, 49, 50, 51, 52, 54, 54, 55, 56, 57, 58, 60, 60, 62, 62, 63, 64, 65, 66, 68, 68, 69, 70, 72, 72
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OFFSET
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1,1
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LINKS
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FORMULA
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a(1) = a(2) = 4. For n >= 3, a(n) = A014683(n).
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MAPLE
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# This Maple program returns the smallest composite greater than n - N. J. A. Sloane, Sep 11 2019
iscomp := n-> if isprime(n) or (n=1) then false else true; fi;
f := proc(n) local a; global iscomp; a:=n+1; while not iscomp(a) do a:=a+1; od; a; end;
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MATHEMATICA
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Table[k = n; While[! CompositeQ@ k, k++]; k, {n, 72}] (* Michael De Vlieger, Sep 06 2017 *)
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PROG
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(Haskell)
a113646 n = if n < 3 then 4 else a014683 n
(Python)
from sympy import isprime
def a(n):
an = max(4, n)
while isprime(an): an += 1
return an
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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