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A172055
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n-th number k such that 6*k-1 is composite while 6*k+1 is prime plus n-th number m such that 6*m-1 is prime while 6*m+1 is composite.
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1
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10, 19, 22, 30, 36, 45, 49, 63, 66, 85, 93, 98, 100, 110, 115, 122, 126, 132, 138, 143, 155, 158, 168, 171, 178, 185, 187, 198, 206, 213, 217, 229, 231, 236, 239, 243, 248, 255, 269, 275, 284, 293, 300, 309, 317, 321, 325, 331, 337, 343, 349, 351, 357, 378
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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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MAPLE
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A121765:=select(k->not isprime(6*k-1) and isprime(6*k+1), [$1..350]):
A121763:=select(n->not isprime(6*n+1) and isprime(6*n-1), [$1..350]):
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MATHEMATICA
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A121765:= Select[Range[350], !PrimeQ[6#-1] && PrimeQ[6#+1] &];
A121763:= Select[Range[350], PrimeQ[6#-1] && !PrimeQ[6#+1] &];
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PROG
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(Magma)
A121765:=[n: n in [1..350] | not IsPrime(6*n-1) and IsPrime(6*n+1)];
A121763:=[n: n in [1..350] | IsPrime(6*n-1) and not IsPrime(6*n+1)];
(Sage)
A121765=[n for n in (1..350) if not is_prime(6*n-1) and is_prime(6*n+1)];
A121763=[n for n in (1..350) if is_prime(6*n-1) and not is_prime(6*n+1)];
(GAP)
A121765:=Filtered([1..350], k-> not IsPrime(6*k-1) and IsPrime(6*k+1));;
A121763:=Filtered([1..350], n-> not IsPrime(6*n+1) and IsPrime(6*n-1));;
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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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