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A002645 Quartan primes: primes of the form x^4 + y^4, x>0, y>0.
(Formerly M5042 N2178)
15
2, 17, 97, 257, 337, 641, 881, 1297, 2417, 2657, 3697, 4177, 4721, 6577, 10657, 12401, 14657, 14897, 15937, 16561, 28817, 38561, 39041, 49297, 54721, 65537, 65617, 66161, 66977, 80177, 83537, 83777, 89041, 105601, 107377, 119617, 121937 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes in the set {A000583 + A000583}. - Jonathan Vos Post, Sep 23 2006

The largest known quartan prime is currently the largest known generalized Fermat prime: The 1353265-digit 145310^262144+1 = (145310^65536)^4+1^4, found by Ricky L Hubbard. - Jens Kruse Andersen, Mar 20 2011

A256852(A049084(a(n))) > 1 for n > 1. - Reinhard Zumkeller, Apr 11 2015

REFERENCES

A. J. C. Cunningham, Binomial Factorisations, Vols. 1-9, Hodgson, London, 1923-1929; see Vol. 1, pp. 245-259.

N. D. Elkies, Primes of the form a^4 + b^4, Mathematical Buds, Ed. H. D. Ruderman Vol. 3 Chap. 3 pp. 22-8 Mu Alpha Theta 1984.

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

T. D. Noe and Moshe Levin, Table of n, a(n) for n = 1..10000 (First 1000 terms from T. D. Noe).

A. J. C. Cunningham, High quartan factorisations and primes, Messenger of Mathematics 36 (1907), pp. 145-174.

A. J. C. Cunningham, Binomial Factorisations, Vols. 1-9, Hodgson, London, 1923-1929. [Annotated scans of a few pages from Volumes 1 and 2]

FORMULA

A000040 INTERSECTION A003336. - Jonathan Vos Post, Sep 23 2006

EXAMPLE

a(1) = 2 = 1^4 + 1^4.

a(2) = 17 = 1^4 + 2^4.

a(3) = 97 = 2^4 + 3^4.

a(4) = 257 = 1^4 + 4^4.

MATHEMATICA

nn = 100000; Sort[Reap[Do[n = a^4 + b^4; If[n <= nn && PrimeQ[n], Sow[n]], {a, nn^(1/4)}, {b, a}]][[2, 1]]]

PROG

(PARI) upto(lim)=my(v=List(2), t); forstep(x=1, lim^.25, 2, forstep(y=2, (lim-x^4)^.25, 2, if(isprime(t=x^4+y^4), listput(v, t)))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 05 2011

(Haskell)

a002645 n = a002645_list !! (n-1)

a002645_list = 2 : (map a000040 $ filter ((> 1) . a256852) [1..])

-- Reinhard Zumkeller, Apr 11 2015

CROSSREFS

Subsequence of A002313.

Cf. A002646, A000040, A000583, A003336.

Cf. A000290, A256852, subsequence of A028916.

Sequence in context: A181546 A081744 A219757 * A100268 A163790 A129123

Adjacent sequences:  A002642 A002643 A002644 * A002646 A002647 A002648

KEYWORD

nonn,easy,changed

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Victoria A Sapko (vsapko(AT)canes.gsw.edu), Nov 07 2002

STATUS

approved

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Last modified July 29 01:01 EDT 2015. Contains 260101 sequences.