A063793 - OEIS

%I #6 Apr 30 2015 10:17:03

%S 7,23,89,199,113,523,887,1669,4297,5591,30593,16141,15683,28229,35617,

%T 43331,34061,134513,31397,404597,542603,461717,404851,604073,1444309,

%U 1388483,2238823,1468277,492113,3851459,1357201,3826019,7621259,13626257,8421251,49269581

%N a(n) = Min{ q prime | nextprime(q) - q - 1 = prime(n)}, or 0 if none exist.

%C Conjecture: a(n) > 0 for n > 1.

%H Charles R Greathouse IV, <a href="/A063793/b063793.txt">Table of n, a(n) for n = 2..217</a>

%F a(n) = A000230((prime(n)+1)/2). - _Charles R Greathouse IV_, Apr 30 2015

%e The 3rd odd prime is 7 = 97 - 89 - 1 and for all p < 89 nextprime(p) - p <> 8; therefore a(3) = 89.

%o (PARI) a(n)=my(t=prime(n)+1,p=2); forprime(q=3,, if(q-p==t, return(p)); p=q) \\ _Charles R Greathouse IV_, Apr 30 2015

%Y Cf. A046933.

%K nonn

%O 2,1

%A _Reinhard Zumkeller_, Aug 18 2001

%E Offset changed by _Charles R Greathouse IV_, Apr 30 2015

%E a(26)-a(37) from _Charles R Greathouse IV_, Apr 30 2015