cp's OEIS Frontend

A114263 Smallest number m such that prime(n) + 2*prime(n+m) is a prime.

%I A114263 #5 Oct 31 2013 17:37:51
%S A114263 1,1,1,1,1,4,5,3,2,2,3,1,1,4,5,1,5,4,2,2,2,2,1,3,1,1,8,4,1,1,2,3,9,2,
%T A114263 5,2,2,9,6,1,1,1,1,2,3,4,1,4,5,8,11,1,11,4,5,1,4,1,5,8,1,1,1,1,2,5,1,
%U A114263 5,9,2,1,10,3,4,4,5,5,6,7,4,1,1,2,4,13,6,6,6,7,9,1,3,1,7,3,9,1,3,3,6,3,8,2
%N A114263 Smallest number m such that prime(n) + 2*prime(n+m) is a prime.
%H A114263 Reinhard Zumkeller, <a href="/A114263/b114263.txt">Table of n, a(n) for n = 2..10000</a>
%e A114263 n=2: prime(2)+2*prime(2+1)=3+2*5=13 is prime, so a(2)=1;
%e A114263 n=3: prime(3)+2*prime(3+1)=5+2*7=19 is prime, so a(2)=1;
%e A114263 ...
%e A114263 n=7: prime(7)+2*prime(7+1)=17+2*19=55 is not prime
%e A114263 ...
%e A114263 prime(7)+2*prime(7+4)=17+2*31=79 is prime, so a(7)=4;
%t A114263 Table[p1 = Prime[n1]; n2 = 1; p2 = Prime[n1 + n2]; While[cp = p1 + 2* p2; ! PrimeQ[cp], n2++; p2 = Prime[n1 + n2]]; n2, {n1, 2, 201}]
%o A114263 (Haskell)
%o A114263 a114263 n = head [m | m <- [1..n],
%o A114263                       a010051 (a000040 n + 2 * a000040 (n + m)) == 1]
%o A114263 -- _Reinhard Zumkeller_, Oct 31 2013
%Y A114263 Cf. A114227, A114230, A073703, A114235, A114262, A114228, A114231, A114233, A114236.
%Y A114263 Cf. A010051, A000040.
%K A114263 easy,nonn
%O A114263 2,6
%A A114263 _Lei Zhou_, Nov 20 2005
%E A114263 Edited definition to conform to OEIS style. - _Reinhard Zumkeller_, Oct 31 2013