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A007521 Primes of the form 8k + 5.
(Formerly M3828)
51

%I M3828 #61 Sep 08 2022 08:44:35

%S 5,13,29,37,53,61,101,109,149,157,173,181,197,229,269,277,293,317,349,

%T 373,389,397,421,461,509,541,557,613,653,661,677,701,709,733,757,773,

%U 797,821,829,853,877,941,997,1013,1021,1061,1069,1093,1109,1117,1181,1213

%N Primes of the form 8k + 5.

%C Primes of the form 4x^2 - 4xy + 5y^2 with x and y nonnegative. - _T. D. Noe_, May 08 2005

%C Prime numbers 2k+1 with k even such that 2k+1 | 2^k+1. - _Hilko Koning_, Jan 21 2022

%D Milton Abramowitz and Irene A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 870.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Ray Chandler, <a href="/A007521/b007521.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from T. D. Noe)

%H Milton Abramowitz and Irene A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

%t Select[8Range[0, 160] + 5, PrimeQ] (* _Harvey P. Dale_, Apr 22 2011 *)

%o (PARI) list(lim)=select(n->n%8==5,primes(primepi(lim))) \\ _Charles R Greathouse IV_, Jul 25 2011

%o (Haskell)

%o a007521 n = a007521_list !! (n-1)

%o a007521_list = filter ((== 1). a010051) a004770_list

%o -- _Reinhard Zumkeller_, Aug 17 2012

%o (Magma) [p: p in PrimesUpTo(2000) | p mod 8 eq 5]; // _Vincenzo Librandi_, Jun 26 2014

%o (Python)

%o from sympy import isprime

%o print(list(filter(isprime, range(5, 1214, 8)))) # _Michael S. Branicky_, May 13 2021

%Y Cf. A010051.

%Y Subsequence of A004770; see also A045323.

%K nonn,easy,nice

%O 1,1

%A _N. J. A. Sloane_, _Robert G. Wilson v_

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Last modified March 19 04:26 EDT 2024. Contains 370952 sequences. (Running on oeis4.)