A253639 Lesser of twin primes of the form (k^2 + 2, k^2 + 4).

3, 11, 227, 1091, 2027, 3251, 13691, 21611, 59051, 65027, 91811, 140627, 178931, 199811, 205211, 227531, 328331, 567011, 700571, 804611, 815411, 1071227, 2241011, 3629027, 4223027, 4347227, 4809251, 5212091, 5919491, 6185171, 6426227, 6671891, 7601051, 7969331, 8661251, 8732027, 9018011, 10323371

Offset: 1

Author

M. F. Hasler, Jan 16 2015

Keywords

• easy
• nonn

Comments

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

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

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

Programs

Mathematica

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

PARI

forstep(x=1,9999,2,is_A086381(x)&&print1(x^2+2,",")) \\ M. F. Hasler, Jan 16 2015

Formula

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