A199924 Numbers k such that the sum of the largest and the smallest prime divisor of k^2 + 1 equals the sum of the other distinct prime divisors.

948, 1560, 1772, 2153, 2697, 8487, 11293, 12553, 13236, 18065, 32247, 36984, 40452, 43999, 55945, 94536, 100512, 107607, 127224, 134223, 214641, 218783, 366937, 425808, 429855, 595471, 620865, 645327, 757382, 850416, 875784, 1241106, 1330849, 1363977, 1387689

Offset

1,1

Comments

Generalization of A192770 and A192771.

Links

Amiram Eldar, Table of n, a(n) for n = 1..200

Example

2697 is in the sequence because 2697^2 + 1 = 7273810 has five distinct divisors  2, 5, 41, 113, 157 and 157 + 2 = 5 + 41 + 113 = 159.

Mathematica

Select[Range[1400000], Plus@@((pl=First/@FactorInteger[#^2+1])/2)==pl[[1]]+pl[[-1]]&](* program of Ray Chandler adapted for this sequence - see A199745 *)

Crossrefs

Cf. A180278, A192771, A192770.

Sequence in context: A257722 A093247 A248785 * A215950 A192770 A187627

Adjacent sequences: A199921 A199922 A199923 * A199925 A199926 A199927

Keyword

nonn

Author

Michel Lagneau, Nov 12 2011

Status

approved