A108570 Squares of lesser of twin primes.

9, 25, 121, 289, 841, 1681, 3481, 5041, 10201, 11449, 18769, 22201, 32041, 36481, 38809, 51529, 57121, 72361, 78961, 96721, 120409, 175561, 185761, 212521, 271441, 323761, 358801, 380689, 410881, 434281, 654481, 674041, 683929, 734449, 776161

Offset: 1

Author

Giovanni Teofilatto, Jul 05 2005

Keywords

• easy
• nonn

Comments

Squares of the form prime(n)*prime(n+1) - 2*prime(n).

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Subsequence of A330477.

Cf. A001359, A108604.

Programs

Magma

[p^2 : p in PrimesUpTo(1100)| IsPrime(p+2)]; // Vincenzo Librandi, Dec 23 2019

Maple

ZL:=[]:for p from 1 to 950 do if (isprime(p) and isprime(p+2)) then ZL:=[op(ZL),(p^2)]; fi; od; print(ZL); # Zerinvary Lajos, Mar 08 2007

Mathematica

Select[First[#]Last[#]-2First[#]&/@Partition[Prime[Range[500]],2,1],IntegerQ[ Sqrt[#]]&] (* Harvey P. Dale, May 24 2011 *)

PARI

p=2;forprime(q=3,, if(q-p==2, print1(p^2", ")); p=q) \\ Charles R Greathouse IV, Dec 16 2019

Extensions

Extended by Ray Chandler, Jul 10 2005

Name and comment swapped by Charles R Greathouse IV, Dec 16 2019