1,2

Where A162488 are numbers x such that x^y+y^x is prime (for some y>1, y<x) and A162489 is least y such that x^y+y^x is prime (for x=A162488(n)).

Table of n, a(n) for n=1..26.

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.

Cf. A094133, A162488, A162489.

Sequence in context: A075696 A061120 A078835 * A031021 A153245 A317670

Adjacent sequences: A173414 A173415 A173416 * A173418 A173419 A173420

nonn

Juri-Stepan Gerasimov, Mar 02 2010

approved