A229266 - OEIS

A229266

Primes of the form sigma(n) + tau(n) + phi(n), where sigma(n) = A000203(n), tau(n) = A000005(n) and phi(n) = A000010(n).

3, 23, 557, 1289, 2447, 3779, 9209, 10331, 11351, 18367, 14051, 34351, 42953, 67883, 95717, 96587, 134807, 164249, 193057, 310553, 253159, 321397, 383723, 548213, 657311, 499151, 630023, 516251, 732181, 713927, 927013, 932431, 784627, 906473, 855331, 1121987

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

The third term of A229265 is 200 and sigma(200) + tau(200) + phi(200) = 465 + 12 + 80 = 557 is prime.

MAPLE

with(numtheory); P:=proc(q) local a, n; for n from 1 to q do a:=sigma(n)+tau(n)+phi(n);

if isprime(a) then print(a); fi; od; end: P(10^6);

MATHEMATICA

Select[Table[DivisorSigma[0, n]+DivisorSigma[1, n]+EulerPhi[n], {n, 10^6}], PrimeQ] (* Harvey P. Dale, Oct 03 2023 *)