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A158806 Numbers n such that 30*n + 19 is prime. 9
0, 2, 3, 4, 6, 7, 11, 12, 13, 14, 16, 20, 23, 24, 25, 27, 28, 30, 33, 34, 35, 37, 41, 42, 46, 47, 48, 49, 51, 52, 53, 55, 56, 58, 59, 62, 66, 67, 69, 72, 74, 75, 79, 84, 88, 89, 90, 91, 100, 101, 102, 103, 105, 107, 108, 110, 115, 116, 117, 118, 123, 124, 125, 129, 130 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Encoded primes with LSD 9, (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.
LINKS
FORMULA
a(n) = (A132234(n) - 19)/30 = Floor[A132234(n)/30]. - Chandler
EXAMPLE
Example: 3019, with LSD 9, (SOD-1)/3 integer; Then 3019/30 = 100.633, or 100, which is in the sequence, thus 3019 is prime.
PROG
(PARI) is(n)=isprime(30*n+19) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Sequence in context: A050679 A342684 A344625 * A184966 A018723 A088412
KEYWORD
nonn
AUTHOR
Ki Punches, Mar 27 2009
EXTENSIONS
Edited by Ray Chandler, Apr 07 2009
STATUS
approved

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Last modified May 27 16:57 EDT 2024. Contains 372880 sequences. (Running on oeis4.)