login
A123597
Primes of the form p^3 + q^3 + r^3, where p, q and r are primes.
2
43, 179, 277, 359, 397, 593, 811, 1483, 2017, 2213, 2251, 2447, 2689, 4421, 4519, 4967, 5381, 6271, 7109, 7229, 9181, 9521, 10169, 11897, 12853, 13103, 13841, 14489, 16561, 17107, 20357, 24443, 24677, 25747, 26711, 27917, 30161, 30259, 31193, 31247, 32579, 36161
OFFSET
1,1
COMMENTS
a(n) is a subset of A007490(n) = {3, 17, 29, 43, 73, 127, 179, 197, 251, 277, ...}, i.e., primes of the form x^3 + y^3 + z^3.
EXAMPLE
a(1) = 43 because 43 = 2^3 + 2^3 + 3^3 is prime and 2^3 + 2^3 + 2^3 = 24 is composite.
MATHEMATICA
lst={}; Do[Do[Do[p=n^3+m^3+k^3; If[PrimeQ[p]&&PrimeQ[n]&&PrimeQ[m]&&PrimeQ[k], AppendTo[lst, p]], {n, 4!}], {m, 4!}], {k, 4!}]; Take[Union[lst], 16] (* Vladimir Joseph Stephan Orlovsky, May 23 2009 *)
With[{nn=40}, Select[Total/@Tuples[Prime[Range[nn]]^3, 3], PrimeQ[#]&&#<= nn^3+ 16&]]//Union (* Harvey P. Dale, Sep 08 2021 *)
CROSSREFS
Cf. A007490 = Primes of form x^3 + y^3 + z^3.
Sequence in context: A162295 A187722 A158628 * A138631 A309905 A142115
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Nov 14 2006
STATUS
approved