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

1,3

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.

Links

Table of n, a(n) for n=1..68.

Formula

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

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

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

Sequence in context: A026482 A232803 A117346 * A039078 A073632 A066378

Adjacent sequences: A158645 A158646 A158647 * A158649 A158650 A158651

Keyword

nonn

Author

Ki Punches, Mar 23 2009

Extensions

Edited by Ray Chandler, Apr 07 2009

Status

approved