A002649 Quintan primes: p = (x^5 - y^5)/(x - y).

5, 31, 211, 1031, 2801, 4651, 5261, 6841, 8431, 14251, 17891, 20101, 21121, 22621, 22861, 26321, 30941, 33751, 36061, 41141, 46021, 48871, 51001, 58411, 61051, 88741, 92821, 103801, 109141, 114641, 118061, 125591, 170101, 176641, 209801

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

5 is a term because x^4 + y*x^3 + y^2*x^2 + y^3*x + y^4 = 5 when x=y=1. - N. J. A. Sloane, May 12 2014

References

• A. J. C. Cunningham, Binomial Factorisations, Vols. 1-9, Hodgson, London, 1923-1929; see Vol. 2, p. 200.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..10000
• A. J. C. Cunningham, Binomial Factorisations, Vols. 1-9, Hodgson, London, 1923-1929. [Annotated scans of a few pages from Volumes 1 and 2]

Crossrefs

Cf. A002650.

Programs

PARI

m=10^6; v=[5]; for(x=1, m^(1/4), for(y=1, x-1, n=(x^5-y^5)/(x-y); if(n<=m && isprime(n), v=concat(v,n)))); vecsort(v) \\ Jens Kruse Andersen, Jul 14 2014

Extensions

a(26)-a(35) from Sean A. Irvine, May 08 2014