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Numbers having exactly one divisor d such that for some x also d-x and d+x are divisors.
3

%I #3 Mar 30 2012 18:50:43

%S 6,15,28,40,91,153,190,220,325,496,544,561,572,627,703,861,897,935,

%T 946,1012,1225,1287,1292,1431,1581,1610,1653,1768,1891,2278,2300,2465,

%U 2618,2701,2967,3321,3344,3496,3596,3655,3952,4123,4301,4324,4371

%N Numbers having exactly one divisor d such that for some x also d-x and d+x are divisors.

%C A091009(a(n)) = 1.

%Y Cf. A091013, A091011.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Dec 13 2003