A253639 - OEIS

%I #18 Jan 05 2020 05:56:31

%S 3,11,227,1091,2027,3251,13691,21611,59051,65027,91811,140627,178931,

%T 199811,205211,227531,328331,567011,700571,804611,815411,1071227,

%U 2241011,3629027,4223027,4347227,4809251,5212091,5919491,6185171,6426227,6671891,7601051,7969331,8661251,8732027,9018011,10323371

%N Lesser of twin primes of the form (k^2 + 2, k^2 + 4).

%C Companion sequence to A085554 (which yields the greater of the pair) and A086381 (which lists the x-values). Except for the first term, all values are a(n)=11 (mod 72). - _M. F. Hasler_, Jan 18 2015

%H Amiram Eldar, <a href="/A253639/b253639.txt">Table of n, a(n) for n = 1..10000</a>

%F Equals A059100 o A086381 = A023444 o A085554, i.e., a(n) = A086381(n)^2+2 = A085554(n)-2. - _M. F. Hasler_, Jan 18 2015

%t Transpose[Select[Table[x^2+{2,4},{x,5000}],AllTrue[#,PrimeQ]&]][[1]] (* The program uses the AllTrue function from Mathematica version 10 *)

%o (PARI) forstep(x=1,9999,2,is_A086381(x)&&print1(x^2+2,",")) \\ _M. F. Hasler_, Jan 16 2015

%Y Cf. A001097, A001359, A006512, A085554, A086381, A253640.

%K easy,nonn

%O 1,1

%A _M. F. Hasler_, Jan 16 2015