A108604 Squares of the form prime(k)*prime(k+1) + 2*prime(k+1).

25, 49, 169, 361, 961, 1849, 3721, 5329, 10609, 11881, 19321, 22801, 32761, 37249, 39601, 52441, 58081, 73441, 80089, 97969, 121801, 177241, 187489, 214369, 273529, 326041, 361201, 383161, 413449, 436921, 657721, 677329, 687241, 737881, 779689

Offset: 1

Author

Giovanni Teofilatto, Jul 06 2005

Keywords

• easy
• nonn

Comments

Squares of greater of twin primes.

Links

• Winston de Greef, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006512, A108570.

Programs

Maple

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

Mathematica

Select[Sqrt/@Table[Prime[k]*Prime[k+1]+2Prime[k+1],{k,160}],IntegerQ]^2 (* James C. McMahon, Jan 27 2024 *)

Formula

a(n) = A006512(n)^2.

Extensions

Corrected and extended by Ray Chandler, Jul 10 2005