OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000
EXAMPLE
Third term of A038344 is 9 and sigma(9) + phi(9) = 13 + 6 = 19 is prime.
MAPLE
with(numtheory); P:=proc(q) local a, n; for n from 1 to q do a:=sigma(n)+phi(n);
if isprime(a) then print(a); fi; od; end: P(10^6);
MATHEMATICA
Select[Table[DivisorSigma[1, n]+EulerPhi[n], {n, 30000}], PrimeQ] (* Harvey P. Dale, Apr 30 2018 *)
PROG
(PARI) lista(kmax) = {my(f, s); for(k = 1, kmax, f = factor(k); s= sigma(f) + eulerphi(f); if(isprime(s), print1(s, ", "))); } \\ Amiram Eldar, Nov 19 2024
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Paolo P. Lava, Sep 18 2013
EXTENSIONS
Name corrected by Amiram Eldar, Nov 19 2024
STATUS
approved