A005846 Primes of the form k^2 + k + 41.
41, 43, 47, 53, 61, 71, 83, 97, 113, 131, 151, 173, 197, 223, 251, 281, 313, 347, 383, 421, 461, 503, 547, 593, 641, 691, 743, 797, 853, 911, 971, 1033, 1097, 1163, 1231, 1301, 1373, 1447, 1523, 1601, 1847, 1933, 2111, 2203, 2297, 2393, 2591, 2693, 2797
Offset: 1
Examples
a(39) = 1601 = 39^2 + 39 + 41 is in the sequence because it is prime. 1681 = 40^2 + 40 + 41 is not in the sequence because 1681 = 41*41.
References
- John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See p. 225.
- R. K. Guy, Unsolved Problems Number Theory, Section A1.
- O. Higgins, Another long string of primes, J. Rec. Math., 14 (1981/2) 185.
- Paulo Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 137.
- Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See pp. 139, 149.
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
- James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, page 115.
Links
- Zak Seidov, Table of n, a(n) for n = 1..10000.
- Phil Carmody, Drag Racing Prime Numbers! - _Vladimir Joseph Stephan Orlovsky_, Jul 24 2011
- Richard K. Guy, The strong law of small numbers. Amer. Math. Monthly 95 (1988), no. 8, 697-712. [Annotated scanned copy]
- R. A. Mollin, Prime-producing quadratics, Amer. Math. Monthly 104 (1997), 529-544.
- Jitender Singh, Prime numbers and factorization of polynomials, arXiv:2411.18366 [math.NT], 2024.
- E. Wegrzynowski, Les formules simples qui donnent des nombres premiers en grande quantité
- Eric Weisstein's World of Mathematics, Euler Prime
- Eric Weisstein's World of Mathematics, Prime-Generating Polynomial
Crossrefs
Programs
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GAP
Filtered(List([0..100],n->n^2+n+41),IsPrime); # Muniru A Asiru, Apr 22 2018
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Haskell
a005846 n = a005846_list !! (n-1) a005846_list = filter ((== 1) . a010051) a202018_list -- Reinhard Zumkeller, Dec 09 2011
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Magma
[a: n in [0..55] | IsPrime(a) where a is n^2+n+ 41]; // Vincenzo Librandi, Apr 24 2018
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Maple
for y from 0 to 10 do U := y^2+y+41; if isprime(U) = true then print(U) end if ; end do: # Matt C. Anderson, Jan 04 2013
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Mathematica
Select[Table[n^2 + n + 41, {n, 0, 59}],PrimeQ] (* Alonso del Arte, Dec 08 2011 *)
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PARI
for(n=1,1e3,if(isprime(k=n^2+n+41),print1(k", "))) \\ Charles R Greathouse IV, Jul 25 2011
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PARI
{k=2; n=1; for(x=1, 100000, f=x^2+x+41; g=x^2+3*x+43; a=gcd(f, g-k); if(a>1, k=k+2); if(a==x+2-k/2, print(n" "a); n++))} \\ Mike Winkler, Oct 02 2013
Extensions
More terms from Henry Bottomley, Jun 26 2000
Comments