A162490 Least prime of the form x^y+y^x with x = A162488(n) > y > 1.

17, 593, 32993, 2097593, 59604644783353249, 43143988327398957279342419750374600193, 8589935681, 5052785737795758503064406447721934417290878968063369478337

Offset

1,1

Comments

Sequences A162488 and A162489 list the corresponding x and y values.

Sequence A094133 lists these primes ordered by their size (without multiplicity). See there for more information, links and references.

Links

Table of n, a(n) for n=1..8.

Formula

a(n) = A162488(n)^A162489(n) + A162489(n)^A162488(n).

Example

The least x such that x^y+y^x is prime for some x>y>1 is A162488(1)=3, for y=A162489(1)=2, yielding the prime a(1) = 9 + 8 = 17.

Prog

(PARI) for(i=3, 999, for(j=2, i-1, isprime(i^j+j^i)|next; print1(i^j+j^i", "); break))

Crossrefs

Cf. A094133, A162486 - A162489.

Sequence in context: A041544 A202407 A009709 * A296790 A330516 A142744

Adjacent sequences: A162487 A162488 A162489 * A162491 A162492 A162493

Keyword

nonn

Author

M. F. Hasler, Jul 04 2009

Status

approved