|
|
A107656
|
|
Numbers k such that prime(k) = d(k)*phi(k) + 1, where d(k) is number of positive divisors of k.
|
|
0
|
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
There is no further term up to 5*10^7.
|
|
LINKS
|
|
|
EXAMPLE
|
652245 is in the sequence because prime(652245) = d(652245)*phi(652245) + 1.
|
|
MATHEMATICA
|
Do[If[Prime[n] == DivisorSigma[0, n]*EulerPhi[n] + 1, Print[n]], {n, 50000000}]
|
|
PROG
|
(PARI) lista(pmax) = {my(k = 0, f); forprime(p=1, 1e16, k++; f = factor(k); if(p == numdiv(f)*eulerphi(f)+1, print1(k, ", "))); } \\ Amiram Eldar, Apr 30 2024
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|