A229264 Primes of the form sigma(n) + phi(n), where sigma(n) = A000203(n) and phi(n) = A000010(n).

2, 19, 19, 79, 103, 113, 257, 523, 509, 1151, 1279, 1193, 1579, 2273, 3061, 2389, 2693, 2843, 5003, 4831, 5119, 7411, 5693, 5623, 8623, 6323, 10139, 8933, 18401, 14957, 20411, 20479, 21191, 20123, 29683, 28211, 36833, 55021, 57203, 68743, 48761, 66533, 62423

Offset

1,1

Links

Table of n, a(n) for n=1..43.

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 *)

Crossrefs

Cf. A000005, A000010, A000203, A009087, A023194, A038344, A055813, A062700, A064205, A115919, A141242, A229265-A229268

Sequence in context: A153653 A065643 A038031 * A132129 A125611 A340922

Adjacent sequences: A229261 A229262 A229263 * A229265 A229266 A229267

Keyword

nonn

Author

Paolo P. Lava, Sep 18 2013

Status

approved