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A134621
Numbers such that the arithmetic mean of the 4th power of their prime factors (taken with multiplicity) is a prime.
15
15, 28, 39, 48, 51, 65, 68, 76, 77, 85, 87, 93, 111, 119, 133, 141, 143, 148, 155, 161, 175, 187, 189, 209, 212, 215, 221, 225, 235, 244, 275, 287, 295, 301, 315, 316, 320, 323, 329, 355, 393, 403, 404, 411, 428, 437, 447, 451, 455, 481, 505, 508, 515, 517
OFFSET
1,1
LINKS
EXAMPLE
a(3)=39, since 39=3*13 and (3^4+13^4)/2=14321 which is prime.
KEYWORD
nonn
AUTHOR
Hieronymus Fischer, Nov 11 2007
EXTENSIONS
Minor edits by Hieronymus Fischer, May 06 2013
STATUS
approved