OFFSET
1,3
COMMENTS
Encoded primes with LSD 7 and (SOD-1)/3 non-integer, (LSD, least significant digit; SOD, sum of digits). Divide any such number by 30, if the whole number portion of the quotient is in the sequence, the number is prime.
EXAMPLE
Example: 3557, with LSD 7 and (SOD-1)/3 = 6.333 (non-integer); Then 7557/30 = 118.566, or 118 which is in the sequence, and thus 3557 is prime.
MATHEMATICA
Select[Range[0, 200], PrimeQ[30#+17]&] (* Harvey P. Dale, Mar 21 2018 *)
PROG
(PARI) is(n)=isprime(30*n+17) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Ki Punches, Mar 23 2009
EXTENSIONS
Edited by Ray Chandler, Apr 07 2009
STATUS
approved