A173040 Single primes having no representation of the form n-+d(n), where d(n) is the number of divisors of n.

67, 79, 131, 167, 379, 401, 439, 479, 487, 499, 503, 647, 739, 743, 761, 773, 863, 887, 941, 967, 971, 1109, 1283, 1307, 1373, 1459, 1571, 1583, 1663, 1733, 1867, 2039, 2137, 2207, 2251, 2377, 2393, 2539, 2543, 2579, 2617, 2663, 2699, 2741, 2749, 2797, 2833, 2861, 2957, 3037, 3041, 3079, 3083, 3191

Offset

1,1

Links

Table of n, a(n) for n=1..54.

Mathematica

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]

Crossrefs

Cf. A000005 (divisor function d(n))

Sequence in context: A066475 A106930 A106929 * A091490 A091075 A288409

Adjacent sequences: A173037 A173038 A173039 * A173041 A173042 A173043

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 21 2010

Extensions

Extended and corrected by T. D. Noe, Nov 21 2010

Status

approved