A158648 Numbers n such that 30*n + 17 is prime.

0, 1, 3, 4, 5, 6, 7, 8, 10, 11, 15, 18, 19, 20, 21, 22, 26, 27, 28, 29, 31, 32, 36, 39, 40, 42, 43, 45, 47, 49, 53, 54, 55, 56, 59, 61, 62, 63, 66, 67, 69, 73, 74, 75, 76, 78, 80, 81, 82, 88, 89, 92, 94, 96, 97, 98, 104, 105, 108, 111, 113, 115, 117, 118, 120, 122, 125, 126

Offset: 1

Author

Ki Punches, Mar 23 2009

Keywords

• nonn

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.

Examples

			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.
		

Crossrefs

Cf. A111175, A158573, A158614, A158746, A158791, A158806, A158850.

Programs

Mathematica

Select[Range[0,200],PrimeQ[30#+17]&] (* Harvey P. Dale, Mar 21 2018 *)

PARI

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

Formula

a(n) = (A039949(n) - 17)/30 = Floor[A039949(n)/30]. - Chandler

Extensions

Edited by Ray Chandler, Apr 07 2009