A110013 Squares of the form 4p + 5, where p is a prime.

25, 49, 81, 121, 169, 289, 361, 441, 529, 729, 961, 1089, 1521, 1681, 1849, 2401, 2809, 3249, 3721, 3969, 5041, 5929, 6241, 6889, 7921, 8281, 8649, 9409, 10201, 11449, 11881, 12321, 12769, 14161, 14641, 16641, 17161, 17689, 18769, 19881, 23409

Offset: 1

Author

Giovanni Teofilatto, Sep 03 2005

Keywords

• easy
• nonn

Comments

The sequence contain all squares of greater of twin primes.

Links

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

Crossrefs

Cf. A002327, A002328, A088502.

Cf. A108604.

Programs

Mathematica

Select[4#+5&/@Prime[Range[900]],IntegerQ[Sqrt[#]]&]  (* Harvey P. Dale, Jan 29 2011 *)

Formula

a(n) = 4*A002327(n) + 5 = A088502(n)^2.

Extensions

Corrected and extended by Ray Chandler, Sep 04 2005