A356423 Leyland numbers which are products of two distinct primes.

57, 145, 177, 1649, 7073, 23401, 131361, 423393, 2012174, 4785713, 33555057, 43050817, 177264449, 364568617, 1073792449, 4486784401, 13877119009, 31381070257, 94143190994, 125937424601, 2552470327702, 8796093024057, 33233199005057, 130291290501553, 1628414210130481, 1853020188884609

Offset

1,1

Comments

A squarefree subsequence of Leyland numbers (which are numbers that can be written as a^b + b^a for a, b > 1).

Links

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

Example

57 = 3*19 = 5^2 + 2^5.
2012174 = 2*1006087 = 9^5 + 5^9.
4486784401 = 11*407889491 = 10^9 + 9^10.
2552470327702 = 2*1276235163851 = 13^9 + 9^13.

Crossrefs

Intersection of A076980 and A006881.

Sequence in context: A044308 A044689 A250606 * A044389 A044770 A008877

Adjacent sequences: A356420 A356421 A356422 * A356424 A356425 A356426

Keyword

nonn

Author

Massimo Kofler, Aug 07 2022

Status

approved