A275278 Numbers n >= 0 such that there exists a number m with sigma(m) and sigma(m+n) both prime.

0, 2, 5, 7, 9, 12, 14, 16, 21, 23, 39, 48, 55, 60, 62, 225, 264, 273, 280, 285, 287, 440, 615, 665, 672, 704, 713, 720, 725, 727, 945, 952, 1080, 1368, 1392, 1536, 1560, 1617, 1656, 1665, 1672, 1677, 1679, 1695, 1800, 2040, 2112, 2280, 2328, 2337, 2376, 2385

Offset

1,2

Comments

Nonnegative numbers of the form A023194(i) - A023194(j). - Altug Alkan, Jul 22 2016

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Example

5 is a term since sigma(4) = 7 and sigma(9) = 13 are both prime.
2385 is a term since sigma(16) = 31 and sigma(2401) = 2801 are both prime.

Mathematica

Select[Range[0, 10^3], Function[n, Total@ Boole@ Map[And[PrimeQ@ DivisorSigma[1, #], PrimeQ@ DivisorSigma[1, # + n]] &, Range[10 n]] > 0]] (* Michael De Vlieger, Jul 22 2016 *)

Crossrefs

Cf. A023194.

Sequence in context: A047386 A187416 A243808 * A184007 A003256 A029901

Adjacent sequences: A275275 A275276 A275277 * A275279 A275280 A275281

Keyword

nonn

Author

Chai Wah Wu, Jul 21 2016

Status

approved