A295818 Primes p such that p+d is composite for all divisors d of p^2-1.
76333, 80077, 106243, 115603, 155333, 175963, 224683, 279353, 281207, 299653, 309157, 312253, 314267, 318523, 361093, 413053, 428083, 526997, 533893, 573829, 580093, 605533, 625237, 637243, 655987, 661993, 706633, 708403, 716747, 723803, 737293, 740227, 741347, 741373, 766967, 775757, 776267, 776317
Offset: 1
Keywords
Links
- Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 2000 from Robert Israel)
Programs
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Maple
filter:= p -> isprime(p) and andmap(t -> not isprime(p+t), numtheory:-divisors(p^2-1)): select(filter, [seq(i,i=3..10^6,2)]);
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PARI
is(n) = if(isprime(n), fordiv(n^2-1, d, if(isprime(n+d), return(0))); 1, 0) \\ Iain Fox, Nov 27 2017
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PARI
is(n)=my(o=valuation(n+1,2), f1=factor((n-1)<
Comments