OFFSET
1,2
FORMULA
a(n) = Min{x; gcd(x, A000720(x))=n}.
EXAMPLE
n=253: a(253)=91586, pi(91586)=8855,
gcd(91586, 8855) = 253 first time.
MATHEMATICA
f[x_] := GCD[x, PrimePi[x]]; t=Table[0, {257}]; Do[s=f[n]; If[s<258&&t[[s]]==0, t[[s]]=n], {n, 1, 100000}]; t
Module[{tbl=Table[{x, GCD[x, PrimePi[x]]}, {x, 12000}]}, Table[SelectFirst[ tbl, #[[2]]==n&], {n, 50}]][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Feb 12 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Sep 16 2003
STATUS
approved