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A229264
Prime terns in A065387 in the order of their appearance.
4
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
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
KEYWORD
nonn,changed
AUTHOR
Paolo P. Lava, Sep 18 2013
EXTENSIONS
Name corrected by Amiram Eldar, Nov 19 2024
STATUS
approved