

A030432


Primes of form 10n+7.


18



7, 17, 37, 47, 67, 97, 107, 127, 137, 157, 167, 197, 227, 257, 277, 307, 317, 337, 347, 367, 397, 457, 467, 487, 547, 557, 577, 587, 607, 617, 647, 677, 727, 757, 787, 797, 827, 857, 877, 887, 907, 937, 947, 967, 977, 997, 1087, 1097, 1117, 1187, 1217, 1237
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OFFSET

1,1


COMMENTS

Union of A132231 and A039949. [Ray Chandler, Apr 07 2009]
5 is not quadratic residue of primes of this form.  Vincenzo Librandi, Jun 25 2014


LINKS

Michael B. Porter, Table of n, a(n) for n = 0..100000
A. Granville and G. Martin, Prime number races


FORMULA

a(n) = 10*A102342(n) + 7.
a(n) ~ 4n log n.  Charles R Greathouse IV, Jul 01 2013


MATHEMATICA

Select[Prime@Range[210], Mod[ #, 10] == 7 &] (* Ray Chandler, Nov 07 2006 *)


PROG

(MAGMA) [n: n in [7..1240 by 10]  IsPrime(n)]; // Bruno Berselli, Apr 06 2011
(PARI) is(n)=n%10==7 && isprime(n) \\ Charles R Greathouse IV, Jul 01 2013


CROSSREFS

Cf. A045357, A045380, A049509, A102342.
Sequence in context: A257668 A106095 A153319 * A090147 A211476 A155007
Adjacent sequences: A030429 A030430 A030431 * A030433 A030434 A030435


KEYWORD

nonn,easy


AUTHOR

Warut Roonguthai


EXTENSIONS

Extended by Ray Chandler, Nov 07 2006


STATUS

approved



