OFFSET
1,2
COMMENTS
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
KEYWORD
nonn
AUTHOR
Chai Wah Wu, Jul 21 2016
STATUS
approved