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A085333 a(n) is the least n-th power of a prime that is the sum of two positive cubes, or 0 if no solution exists (for n=3k). 1

%I #12 Dec 20 2019 13:58:00

%S 2,9,0,16,243,0,128,6561,0,1024,177147,0,8192,4782969,0,65536,

%T 129140163,0,524288,3486784401,0,4194304,94143178827,0,33554432,

%U 2541865828329,0,268435456,68630377364883,0,2147483648,1853020188851841,0

%N a(n) is the least n-th power of a prime that is the sum of two positive cubes, or 0 if no solution exists (for n=3k).

%F a(n) is the least solution to p^n=x^3+y^3, x, y>0 or a(n)=a(3k)=0 labels cases if no solution exists.

%F a(3k)=0, a(3k+1)=2^(3k+1), a(3k+2)=3^(3k+2).

%F From _Chai Wah Wu_, May 18 2017: (Start)

%F a(n) = 35*a(n-3) - 216*a(n-6) for n > 6.

%F G.f.: x*(-72*x^4 - 54*x^3 + 9*x + 2)/(216*x^6 - 35*x^3 + 1). (End)

%Y Cf. A085332.

%K nonn

%O 1,1

%A _Labos Elemer_, Jul 07 2003

%E Formula, corrected description and more terms from _Ray Chandler_, Jul 20 2003

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Last modified April 19 16:21 EDT 2024. Contains 371794 sequences. (Running on oeis4.)