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.

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

Amiram Eldar, Table of n, a(n) for n = 1..500

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

Cf. A002522, A014442, A193462, A200071.

Sequence in context: A346219 A035859 A105310 * A261264 A125840 A069984

Adjacent sequences: A200069 A200070 A200071 * A200073 A200074 A200075

Keyword

nonn

Author

Michel Lagneau, Nov 13 2011

Status

approved