A158791 Numbers n such that 30*n + 23 is prime.

0, 1, 2, 3, 5, 7, 8, 9, 11, 12, 14, 16, 18, 19, 21, 22, 24, 25, 28, 31, 32, 33, 36, 38, 39, 40, 42, 45, 47, 49, 50, 51, 52, 53, 57, 60, 63, 65, 66, 68, 71, 73, 74, 75, 77, 79, 80, 84, 87, 88, 89, 91, 94, 96, 98, 100, 102, 106, 110, 113, 117, 119, 120, 126, 127, 128, 130, 133

Offset: 1

Author

Ki Punches, Mar 26 2009

Keywords

• nonn

Comments

Encoded primes with LSD 3 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: 3623, with LSD 3 and (SOD-1)/3 non-integer; Then 3623/30 = 120.766, or 120, which is in the sequence, thus 3623 is prime.
		

Crossrefs

Cf. A111175, A158573, A158614, A158648, A158746, A158806, A158850.

Programs

Mathematica

Select[Range[0,200],PrimeQ[30#+23]&] (* Harvey P. Dale, Jul 31 2014 *)

PARI

is(n)=isprime(30*n+23) \\ Charles R Greathouse IV, Feb 17 2017

Formula

a(n) = (A132235(n) - 23)/30 = Floor[A132235(n)/30]. - Chandler

Extensions

Edited by Ray Chandler, Apr 07 2009