A242902 - OEIS

%I #15 Jul 21 2018 03:29:29

%S 1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,1,0,1,1,0,1,1,1,1,1,0,1,1,1,1,0,1,1,

%T 1,1,0,1,1,0,0,1,1,1,1,0,1,1,1,1,0,1,1,0,1,0,1,0,1,0,1,0,0,1,1,0,1,1,

%U 0,1,1,1,1,1,0

%N a(n) = 1 if either of A014574(n) + A014574(n+2) +- 1 is prime or 0 otherwise.

%C From the first 10000 evaluations (each evaluating the primality of 2 values, though at least 2200 are obvious as multiples of 5), one encounters ~5200 primes. The longest "gap" without prime encounter is 13 evaluations. By design, the procedure encounters primes loosely on the order of twice as large as those used in each evaluation.

%H Charles R Greathouse IV, <a href="/A242902/b242902.txt">Table of n, a(n) for n = 1..10000</a>

%e A014574(2)=6 and A014574(4)=18. (18+6) +-1 yields 23, 25. 23 is prime, so a(2)=1.

%e A014574(12)=150 and A014574(14)=192, which yields 341, 343. Neither is prime, so a(12)=0.

%o (PARI) v=[0, 4, 6]; p=11; forprime(q=13,, if(q-p==2, v=[v[2],v[3],p+1]; print1(isprime(v[1]+v[3]+1)||isprime(v[1]+v[3]-1), ", ")); p=q) \\ _Charles R Greathouse IV_, May 25 2014

%Y Cf. A014574.

%K nonn

%O 1

%A _Bill McEachen_, May 25 2014