cp's OEIS Frontend

A114235 Largest prime p < prime(n) such that 2*prime(n) + p is a prime.

%I A114235 #7 Oct 31 2013 17:34:59
%S A114235 3,5,7,11,13,5,13,13,17,29,31,41,43,43,31,59,59,37,53,71,73,79,89,79,
%T A114235 101,103,89,67,113,127,127,131,103,137,149,137,157,163,163,179,181,
%U A114235 191,193,179,197,197,223,173,211,223,227,241,229,193,223,269,269,277,263
%N A114235 Largest prime p < prime(n) such that 2*prime(n) + p is a prime.
%H A114235 Reinhard Zumkeller, <a href="/A114235/b114235.txt">Table of n, a(n) for n = 3..10000</a>
%e A114235 n=3: 2*prime(3)+3=2*5+3=13 is prime, so a(3)=3;
%e A114235 n=4: 2*prime(4)+5=2*7+5=19 is prime, so a(4)=5;
%e A114235 ...
%e A114235 n=8: 2*prime(8)+17=2*19+17=55 is not prime
%e A114235 2*prime(8)+13=2*19+13=51 is not prime
%e A114235 ...
%e A114235 2*prime(8)+5=2*19+5=43 is prime, so a(8)=5;
%t A114235 Table[p1 = Prime[n1]; n2 = 1; p2 = Prime[n1 - n2]; While[cp = 2*p1 + p2; ! PrimeQ[cp], n2++; If[n2 >= n1, Print[n1]]; p2 = Prime[n1 - n2]]; p2, {n1, 3, 202}]
%o A114235 (Haskell)
%o A114235 a114235 n = head [p | let q = a000040 n,
%o A114235                       p <- reverse $ takeWhile (< q) a000040_list,
%o A114235                       a010051 (2 * q + p) == 1]
%o A114235 -- _Reinhard Zumkeller_, Oct 29 2013
%Y A114235 Cf. A114227, A114230, A073703.
%Y A114235 Cf. A000040, A010051.
%K A114235 easy,nonn
%O A114235 3,1
%A A114235 _Lei Zhou_, Nov 20 2005
%E A114235 Edited definition to conform to OEIS style. - _Reinhard Zumkeller_, Oct 29 2013