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Primes congruent to 31 mod 40.
1

%I #9 Sep 08 2022 08:45:35

%S 31,71,151,191,271,311,431,631,751,911,991,1031,1151,1231,1471,1511,

%T 1831,1871,1951,2111,2311,2351,2551,2591,2671,2711,2791,3191,3271,

%U 3391,3511,3631,3671,3911,4111,4231,4271,4391,4591,4751,4831,4871,4951,5231,5351

%N Primes congruent to 31 mod 40.

%H Vincenzo Librandi, <a href="/A142195/b142195.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) ~ 16n log n. - _Charles R Greathouse IV_, Jul 03 2016

%t Select[Prime[Range[2000]],MemberQ[{31},Mod[#,40]]&] (* _Vincenzo Librandi_, Aug 22 2012 *)

%o (Magma) [p: p in PrimesUpTo(7000) | p mod 40 eq 31 ]; // _Vincenzo Librandi_, Aug 22 2012

%o (PARI) is(n)=isprime(n) && n%40==31 \\ _Charles R Greathouse IV_, Jul 03 2016

%Y Cf. A000040.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_, Jul 11 2008