A363896 Numbers k such that the sum of primes dividing k (with repetition) is equal to Euler's totient function of k.
9, 15, 16, 42
Offset: 1
Crossrefs
Programs
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Mathematica
Select[Range[2, 1000], EulerPhi[#] == Plus @@ Times @@@ FactorInteger[#] &] (* Amiram Eldar, Jun 27 2023 *)
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PARI
is(k) = my(f=factor(k)); f[, 1]~*f[, 2] == eulerphi(f); \\ Amiram Eldar, Jun 27 2023
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Python
from sympy import factorint,totient A001414 = lambda k: sum(p*e for p, e in factorint(k).items()) def g(): k = 2 while True: if A001414(k) == totient(k): yield(k) k += 1 for a_n in g(): print(a_n)
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