OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..15628 (terms below 10^5; terms 1..316 from Robert Israel)
EXAMPLE
6 = cototient(10) and for all x<>10, cototient(x) <> 6.
MAPLE
N:= 1000: # for all terms <= N
cotot:= n -> n - numtheory:-phi(n):
V:= Vector(N):
for n from 2 to N^2 do
v:= cotot(n);
if v > N then next fi;
V[v]:= V[v]+1;
od:
0, op(select(t -> V[t]=1, [$1..N])); # Robert Israel, May 26 2019
PROG
(PARI) lista(nn) = {my(v=vector(nn^2+2, i, i - eulerphi(i))); for(k=0, nn, if(sum(i=1, k*k+2, k==v[i])==1, print1(k, ", "))); } \\ Jinyuan Wang, Mar 21 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Franz Vrabec, Jul 19 2007
EXTENSIONS
More terms from Robert Israel, May 26 2019
STATUS
approved