OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..500
FORMULA
a(n) = Min{x; A070803(x)=n};
MATHEMATICA
{0}~Join~Table[x = 1; While[PrimePi@ DivisorSigma[1, x] != n, x++]; x, {n, 2, 63}] (* Michael De Vlieger, Feb 05 2017 *)
PROG
(PARI) a(n) = if (n==1, 0, x = 1; while(primepi(sigma(x))!= n, x++); x); \\ Michel Marcus, Dec 11 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 10 2003
STATUS
approved