A158746 Numbers n such that 30*n + 13 is prime.

0, 1, 2, 3, 5, 6, 7, 9, 10, 12, 14, 15, 17, 20, 21, 22, 24, 27, 28, 29, 34, 35, 36, 37, 38, 40, 43, 47, 48, 49, 51, 55, 56, 57, 58, 59, 62, 64, 66, 68, 69, 70, 71, 73, 76, 79, 82, 83, 86, 89, 90, 93, 94, 98, 105, 108, 110, 111, 112, 114, 115, 119, 120, 121, 122, 124, 126, 127

Offset: 1

Author

Ki Punches, Mar 25 2009

Keywords

• nonn

Comments

Encoded primes with LSD 3, (SOD-1)/3 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.

Examples

			Example: 3163, with LSD 3 and (SOD-1)/3 = 4 (integer); Then 3163/30 = 105.433, or 105 which is in the sequence, thus 3163 is prime.
		

Crossrefs

Cf. A111175, A158573, A158614, A158648, A158791, A158806, A158850.

Programs

Mathematica

Select[Range[0,200],PrimeQ[30#+13]&] (* Harvey P. Dale, Oct 16 2018 *)

PARI

is(n)=isprime(30*n+13) \\ Charles R Greathouse IV, Feb 17 2017

Formula

a(n) = (A132233(n) - 13)/30 = Floor[A132233(n)/30]. - Chandler

Extensions

Edited by Ray Chandler, Apr 07 2009