OFFSET
2,1
COMMENTS
The sum of the reciprocals = 0.40100980056022072540219852776239... . Converges rapidly.
FORMULA
a(n) = floor( sqrt(1/x)*10^(floor(sqrt(x))) ), where x = prime(n).
MATHEMATICA
a[n_] := Module[{r = Sqrt[Prime[n]], ip, fp}, ip = Floor[r]; fp = r - ip; Floor[10^ip/r]]; Array[a, 40] (* Amiram Eldar, Jun 26 2024 *)
PROG
(PARI) rootrecipp(n) = { my(sr=0, r, ip, fp, y); forprime(x=2, n, r =sqrt(x); ip=floor(r); fp=r-ip; y=floor((1/r)*10^ip); print1(y", "); sr = sr + 1.0/y; ); print(); print(sr) }
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Dec 11 2003
EXTENSIONS
More terms from Amiram Eldar, Jun 26 2024
STATUS
approved