A069262 a(n) = 4*prime(n)^2.

16, 36, 100, 196, 484, 676, 1156, 1444, 2116, 3364, 3844, 5476, 6724, 7396, 8836, 11236, 13924, 14884, 17956, 20164, 21316, 24964, 27556, 31684, 37636, 40804, 42436, 45796, 47524, 51076, 64516, 68644, 75076, 77284, 88804, 91204, 98596

Offset: 1

Author

Benoit Cloitre, Apr 14 2002

Keywords

• easy
• nonn

Comments

Previous name was: Numbers n such that sum(d|n,(-1)^d) = 3.

Links

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

Crossrefs

Cf. A001248, A048272.

Programs

Magma

[4*p^2: p in PrimesUpTo(200)]; // Vincenzo Librandi, Mar 27 2014

Mathematica

4 Prime[Range[40]]^2 (* Vincenzo Librandi, Mar 27 2014 *)

PARI

a(n) = 4*prime(n)^2; \\ Michel Marcus, Mar 23 2016

PARI

lista(nn) = {forprime(p=2, nn, print1(4*p^2, ", "));} \\ Altug Alkan, Mar 23 2016

Formula

a(n) = 4*prime(n)^2 = 4*A001248(n).

Numbers k such that A048272(k) = -3.

Sum_{n>=1} 1/a(n) = P(2)/4, where P is the prime zeta function. - Amiram Eldar, Dec 19 2020

Extensions

New name from existing formula by Michel Marcus, Mar 23 2016