

A102342


Numbers k such that 10k + 7 is prime.


11



0, 1, 3, 4, 6, 9, 10, 12, 13, 15, 16, 19, 22, 25, 27, 30, 31, 33, 34, 36, 39, 45, 46, 48, 54, 55, 57, 58, 60, 61, 64, 67, 72, 75, 78, 79, 82, 85, 87, 88, 90, 93, 94, 96, 97, 99, 108, 109, 111, 118, 121, 123, 127, 129, 130, 132, 136, 142, 144, 148, 156, 159, 160, 162, 163
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OFFSET

1,3


COMMENTS

Solutions of the equation (10*k+7)'=1, where k' is the arithmetic derivative of k.  Paolo P. Lava, Nov 15 2012


LINKS

Table of n, a(n) for n=1..65.


EXAMPLE

10*1 + 7 = 17 (prime);
10*48 + 7 = 487 (prime);
10*99 + 7 = 997 (prime).


MATHEMATICA

Select[Range[0, 170], PrimeQ[10# + 7] &] (* Ray Chandler, Nov 07 2006 *)


PROG

(MAGMA) [n: n in [0..3000] IsPrime(10*n+7)]; // Vincenzo Librandi, Apr 06 2011
(PARI) is(n)=isprime(10*n+7) \\ Charles R Greathouse IV, Feb 17 2017


CROSSREFS

Cf. A030432, A049509.
Sequence in context: A325440 A080710 A115837 * A286692 A014419 A138670
Adjacent sequences: A102339 A102340 A102341 * A102343 A102344 A102345


KEYWORD

nonn


AUTHOR

Parthasarathy Nambi, Feb 20 2005


EXTENSIONS

Edited and extended by Ray Chandler, Nov 07 2006


STATUS

approved



