A173417 Either A162488(n)-+A162489(n) is prime.

1, 7, 12, 14, 16, 20, 21, 22, 24, 25, 27, 28, 29, 33, 35, 39, 40, 41, 44, 45, 47, 49, 52, 53, 54, 55

Offset: 1

Author

Juri-Stepan Gerasimov, Mar 02 2010

Keywords

• nonn

Comments

Where A162488 are numbers x such that x^y+y^x is prime (for some y>1, yA162489 is least y such that x^y+y^x is prime (for x=A162488(n)).

Examples

			a(1)=1 because A162488(1)-A162489(1)=1=nonprime and A162488(1)+A162489(1)=5=prime; a(2)=7 because A162488(7)-A162489(7)=31=prime and A162488(7)+A162489(7)=35=nonprime.
		

Crossrefs

Cf. A094133, A162488, A162489.