

A099049


Numbers n such that n1 and n+1 are both prime or both composite.


1



4, 5, 6, 7, 9, 11, 12, 13, 15, 17, 18, 19, 21, 23, 25, 26, 27, 29, 30, 31, 33, 34, 35, 37, 39, 41, 42, 43, 45, 47, 49, 50, 51, 53, 55, 56, 57, 59, 60, 61, 63, 64, 65, 67, 69, 71, 72, 73, 75, 76, 77, 79, 81, 83, 85, 86, 87, 89, 91, 92, 93, 94, 95, 97, 99, 101, 102, 103, 105, 107
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OFFSET

1,1


LINKS



MATHEMATICA

Select[Range[120], AllTrue[#+{1, 1}, CompositeQ]AllTrue[#+{1, 1}, PrimeQ]&] (* Harvey P. Dale, Sep 01 2021 *)


PROG

(PARI) for(n=3, 200, s=isprime(n1)+isprime(n+1); if(s<>1, print1(n, ", ")))


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



