OFFSET
1,1
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
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
MATHEMATICA
4 Prime[Range[40]]^2 (* Vincenzo Librandi, Mar 27 2014 *)
PROG
(Magma) [4*p^2: p in PrimesUpTo(200)]; // 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
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 14 2002
EXTENSIONS
New name from existing formula by Michel Marcus, Mar 23 2016
STATUS
approved