OFFSET
1,1
COMMENTS
There must be an odd number of odd terms in the sum, either 5 odd terms (as with 5 = 1^5 + 1^5 + 1^5 + 1^5 + 1^5 and 16811 = 1^5 + 1^5 + 1^5 + 1^5 + 7^5), two even and 3 odd terms (as with 67 = 1^5 + 1^5 + 1^5 + 2^5 + 2^5 and 1301 = 1^5 + 1^5 + 2^5 + 3^5 + 4^5) or four even terms and one odd term (as with 3253 = 2^5 + 2^5 + 2^5 + 2^5 + 5^5). The sum of two positive 5th powers (A003347), other than 2 = 1^5 + 1^5, cannot be prime.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1) = 5 = 1^5 + 1^5 + 1^5 + 1^5 + 1^5.
a(2) = 67 = 1^5 + 1^5 + 1^5 + 2^5 + 2^5.
a(3) = 1301 = 1^5 + 1^5 + 2^5 + 3^5 + 4^5.
a(4) = 1543 = 1^5 + 2^5 + 3^5 + 3^5 + 4^5.
a(5) = 2113 = 1^5 + 2^5 + 2^5 + 4^5 + 4^5.
a(6) = 3191 = 1^5 + 1^5 + 2^5 + 2^5 + 5^5.
a(7) = 4339 = 3^5 + 4^5 + 4^5 + 4^5 + 4^5.
MATHEMATICA
Take[Select[Union[Total/@Tuples[Range[10]^5, 5]], PrimeQ], 60] (* Harvey P. Dale, Jul 21 2014 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Sep 24 2006
EXTENSIONS
Corrected and extended by Harvey P. Dale, Jul 21 2014
STATUS
approved