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A167428
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Smallest non-isolated (or twin) prime > n-th non-isolated nonprime.
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1
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3, 3, 11, 11, 11, 17, 17, 17, 29, 29, 29, 29, 29, 29, 29, 29, 41, 41, 41, 41, 41, 41, 41, 41, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 71, 71, 71, 71, 71, 71, 71, 71, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(1)=3 (>0); a(2)=3 (>1); a(3)=11 (>8); a(4)=11 (>8); a(5)=11 (>10); a(6)=17 (>14).
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MAPLE
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A164276 := proc(n) option remember; if n = 1 then 0; else for a from procname(n-1)+1 do if isA164276(a) then return a; end if; end do; end if: end proc:
isA164276 := proc(n) not isprime(n) and ( not isprime(n+1) or not isprime(n-1) ) ; end proc:
isA001097 := proc(n) isprime(n) and ( isprime(n+2) or isprime(n-2) ); end proc:
A167428 := proc(n) for a from A164276(n)+1 do if isA001097(a) then return a; end if; end do: end proc:
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CROSSREFS
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KEYWORD
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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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