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A158791 Numbers n such that 30*n + 23 is prime. 8
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

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.

LINKS

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

FORMULA

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

EXAMPLE

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.

MATHEMATICA

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

PROG

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

CROSSREFS

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

Sequence in context: A156271 A186513 A246438 * A144717 A202728 A244016

Adjacent sequences:  A158788 A158789 A158790 * A158792 A158793 A158794

KEYWORD

nonn

AUTHOR

Ki Punches, Mar 26 2009

EXTENSIONS

Edited by Ray Chandler, Apr 07 2009

STATUS

approved

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Last modified July 25 15:30 EDT 2021. Contains 346291 sequences. (Running on oeis4.)