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A024913 Numbers n such that 10n - 7 is prime. 1
1, 2, 3, 5, 6, 8, 9, 11, 12, 17, 18, 20, 23, 24, 27, 29, 30, 32, 36, 38, 39, 44, 45, 47, 51, 53, 57, 60, 62, 65, 66, 68, 69, 74, 75, 78, 83, 86, 87, 89, 96, 99, 102, 104, 107, 110, 111, 113, 116, 117, 120, 122, 123, 129, 131, 138, 143, 144, 146, 149, 150, 153, 155, 156, 159, 162, 167 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Solutions of the equation (10*n-7)' = 1, where n' is the arithmetic derivative of n. - Paolo P. Lava, Jan 03 2013

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[500], PrimeQ[10 # - 7] &] (* Vincenzo Librandi, May 19 2014 *)

PROG

(MAGMA) [n: n in [1..1000] |IsPrime(10*n-7)]; Vincenzo Librandi, Nov 19 2010

(PARI) is(n)=isprime(10*n-7) \\ Charles R Greathouse IV, Jun 06 2017

CROSSREFS

Cf. A030431 (associated primes).

Sequence in context: A139364 A211265 A327423 * A284934 A320928 A186225

Adjacent sequences:  A024910 A024911 A024912 * A024914 A024915 A024916

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified May 9 10:14 EDT 2021. Contains 343730 sequences. (Running on oeis4.)