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A200072
Numbers k such that the sum of the prime distinct divisors of k^2+1 equals 2 times the largest prime divisor of k^2+1.
1
1123, 1143, 6235, 8457, 11565, 21917, 22857, 33285, 41319, 58195, 119571, 124723, 128363, 173922, 178703, 188115, 243939, 280158, 308859, 309709, 409485, 430581, 565571, 703845, 961237, 1153362, 1170291, 1327998, 1409794, 1536651, 1586195, 1649395, 1665868
OFFSET
1,1
LINKS
EXAMPLE
1123 is in the sequence because the distinct prime divisors of 1123^2 + 1 are 2, 5, 13, 89, 109 and the sum 2 + 5 + 13 + 89 + 109 = 218 = 2*109.
MATHEMATICA
Select[Range[1700000], Plus@@(pl=First/@FactorInteger[#^2+1])==2*pl[[-1]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Nov 13 2011
STATUS
approved