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A356423
Leyland numbers which are products of two distinct primes.
0
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).
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
KEYWORD
nonn
AUTHOR
Massimo Kofler, Aug 07 2022
STATUS
approved