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Single primes having no representation of the form n-+d(n), where d(n) is the number of divisors of n.
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%I #9 Mar 30 2012 18:52:39

%S 67,79,131,167,379,401,439,479,487,499,503,647,739,743,761,773,863,

%T 887,941,967,971,1109,1283,1307,1373,1459,1571,1583,1663,1733,1867,

%U 2039,2137,2207,2251,2377,2393,2539,2543,2579,2617,2663,2699,2741,2749,2797,2833,2861,2957,3037,3041,3079,3083,3191

%N Single primes having no representation of the form n-+d(n), where d(n) is the number of divisors of n.

%t nn=10000; p=Select[Union[Flatten[Table[d=DivisorSigma[0,n]; {n-d, n+d}, {n,nn}]]], PrimeQ]; Complement[Prime[Range[PrimePi[p[[-1]]]]], p]

%Y Cf. A000005 (divisor function d(n))

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Nov 21 2010

%E Extended and corrected by _T. D. Noe_, Nov 21 2010