OFFSET
1,3
COMMENTS
Encoded primes with LSD 1 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.
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
Example: 3191, with LSD 1 and (SOD-1)/3 = 4.33 (non-integer); Then 3191/30=106.367, or 106 which is in the sequence, thus 3191 is prime.
MATHEMATICA
Select[Range[0, 130], PrimeQ[30#+11]&] (* Harvey P. Dale, Jul 26 2011 *)
PROG
(PARI) is(n)=isprime(30*n+11) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Ki Punches, Mar 22 2009, Mar 29 2009
EXTENSIONS
Edited by Ray Chandler, Apr 07 2009
STATUS
approved