A146981 Numbers k of the form q^2, q = prime, such that k-2 is a prime.

4, 9, 25, 49, 169, 361, 841, 1369, 1849, 2209, 3721, 5041, 7921, 10609, 11449, 16129, 17161, 19321, 29929, 36481, 44521, 49729, 54289, 57121, 66049, 85849, 97969, 113569, 128881, 177241, 196249, 201601, 218089, 241081, 273529, 292681, 323761

Offset: 1

Author

Giovanni Teofilatto, Nov 04 2008

Keywords

• nonn

Comments

Except for initial term, a(n) - 1 is not a squarefree number.

Links

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

Crossrefs

Cf. A049002, A062326.

Programs

Mathematica

Select[Prime[Range[150]]^2,PrimeQ[#-2]&] (* Harvey P. Dale, Jan 15 2020 *)

Formula

a(n) = A049002(n) + 2.

a(n) = A062326(n)^2. - Amiram Eldar, Oct 21 2019

Extensions

Corrected (3721 inserted, 10321 replaced by 19321, 49729 and 218089 inserted) by R. J. Mathar, Apr 22 2010