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A292775 a(n) = smallest prime q such that Sum_{primes p <= q} 1/sqrt(p) >= n. 2
3, 7, 19, 41, 73, 113, 191, 271, 383, 509, 661, 859, 1069, 1307, 1601, 1931, 2287, 2687, 3119, 3583, 4093, 4657, 5279, 5881, 6607, 7351, 8167, 9001, 9851, 10837, 11867, 12899, 13967, 15161, 16361, 17627, 19031, 20389, 21821, 23297, 24917, 26557, 28279, 30059, 31891, 33647, 35617, 37607, 39779 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Benoit Cloitre, Asymptotics for A292775
FORMULA
a(n) ~ prime(n)^2. - Benoit Cloitre, Oct 01 2017 [See link]
MAPLE
Digits:=50;
s0:=0; k:=1; lisi:=[]; lisP:=[];
for i from 1 to 10000 do p:=ithprime(i);
s0:=s0+evalf(1/sqrt(p));
if s0 >= k then k:=k+1; lisi:=[op(lisi), i]; lisP:=[op(lisP), p]; fi;
od:
lisi; # A292774
lisP; # A292775
MATHEMATICA
f[n_]:=Block[{k=0, s=0}, While[s<n, k++; s=N[s+1/Sqrt[Prime[k]], 50]]; k]; Table[Prime[f[n]], {n, 1, 50}] (* Vincenzo Librandi, Oct 01 2017 *)
CROSSREFS
Sequence in context: A281866 A173114 A163572 * A282024 A356617 A086519
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 30 2017
STATUS
approved

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Last modified May 27 21:52 EDT 2024. Contains 372882 sequences. (Running on oeis4.)