OFFSET
1,4
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
G.f.: Sum_{k>=1} prime(k)^2 * x^(prime(k)^2) / (1 - x^prime(k)). - Ilya Gutkovskiy, Aug 19 2021
EXAMPLE
2 and 3 are the distinct prime divisors of 12 and both 2 and 3 are <= sqrt(12), so a(12) = 2^2 + 3^2 = 13.
MATHEMATICA
ssdpd[n_]:=Total[Select[Transpose[FactorInteger[n]][[1]], #<=Sqrt[n]&]^2]; Join[{0}, Array[ssdpd, 90, 2]] (* Harvey P. Dale, Mar 11 2013 *)
PROG
(PARI) a(n) = sumdiv(n, d, isprime(d)*(d^2<=n)*d^2); \\ Michel Marcus, Dec 22 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Sep 08 2004
EXTENSIONS
More terms from John W. Layman, Sep 14 2004
STATUS
approved