A118504 Sophie Germain primes whose sum of digits is also a Sophie Germain prime.
2, 3, 5, 11, 23, 29, 41, 83, 113, 131, 173, 191, 281, 443, 641, 911, 1013, 1019, 1031, 1103, 1451, 1499, 1811, 1901, 2003, 2063, 2351, 2399, 2939, 3299, 3389, 3413, 4793, 4919, 5051, 5231, 5279, 5303, 5501, 5639, 6113, 6131, 6269, 6449, 7079, 7103, 7121, 7211
Offset: 1
Examples
191 is in the sequence because it is a Sophie Germain prime and the sum of its digits 1+9+1 = 11 is also a Sophie Germain prime.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)
Programs
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Mathematica
sgpQ[n_]:=Module[{c=Total[IntegerDigits[n]]},And@@PrimeQ[{2n+1,c,2c+1}]]; Select[Prime[Range[1000]],sgpQ] (* Harvey P. Dale, Oct 14 2012 *)
Extensions
Corrected by T. D. Noe, Oct 25 2006
Corrected by Harvey P. Dale, Oct 14 2012