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 A216439 Smallest k such that k*n^3 + 1 is an n-th power. 3

%I #24 Aug 27 2020 13:35:13

%S 1,1,37,791,95051,111748,2277696793,484679258335,229930796172439,

%T 79792266297612,66954547910007962117,337165646545,

%U 45082285083777592171142467,2379140952844779936142872,60722942736706550906445847537201,78033832840595333890814363993704319

%N Smallest k such that k*n^3 + 1 is an n-th power.

%H Robert Israel, <a href="/A216439/b216439.txt">Table of n, a(n) for n = 1..216</a>

%e a(3) = 37 because 37*3^3 + 1 = 1000 = 10^3.

%p f:= proc(n) local S,x;

%p S:= subs(1=n^3+1, map(t -> rhs(op(t)), [msolve(x^n-1, n^3)]));

%p x:= min(S);

%p (x^n-1)/n^3

%p end proc:

%p f(1):= 1:

%p map(f, [\$1..20]); # _Robert Israel_, Aug 26 2020

%t a={}; Do[k = 2; While[ !IntegerQ[(k^n - 1)/n^3], k++ ]; AppendTo[a, (k^n-1)/n^3], {n, 1, 20}]; a

%Y Cf. A076943, A193746.

%K nonn

%O 1,3

%A _Michel Lagneau_, Sep 10 2012

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Last modified August 7 21:19 EDT 2024. Contains 375017 sequences. (Running on oeis4.)