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A275278 Numbers n >= 0 such that there exists a number m with sigma(m) and sigma(m+n) both prime. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 23 12:35 EST 2019. Contains 320431 sequences. (Running on oeis4.)