OFFSET
1,1
COMMENTS
Subsequence of A120944.
EXAMPLE
Prime factors of 28101 are 3, 17, 19, 29 and tau(28101) = 16, phi(28101) = 16128. 28101 - 16128 = 11973 and 11973 / (3 - 16) = -921, 11973 / (17 - 16) = 11973, 11973 / (19 - 16) = 3991, 11973 / (29 - 16) = 921.
MAPLE
with (numtheory); P:=proc(q) global a, b, c, i, ok, p, n;
for n from 2 to q do if not isprime(n) then a:=ifactors(n)[2]; ok:=1;
for i from 1 to nops(a) do if a[i][2]>1 or a[i][1]=tau(n) then ok:=0; break;
else if not type((n-phi(n))/(a[i][1]-tau(n)), integer) then ok:=0; break; fi; fi; od; if ok=1 then print(n); fi; fi; od; end: P(6*10^9);
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Sep 20 2013
EXTENSIONS
a(9)-a(27) from Giovanni Resta, Sep 20 2013
First term deleted by Paolo P. Lava, Sep 23 2013
STATUS
approved