OFFSET
1,2
COMMENTS
It's not obvious that a(n) exists for all n.
a(967) > 8*10^15 (if it exists). - Donovan Johnson, Sep 04 2013
REFERENCES
A. Choudhry, Indian J. pure appl. Math. 26(11) (1995), 1057-1061
LINKS
Robert Israel and Donovan Johnson, Table of n, a(n) for n = 1..966 (first 205 terms from Robert Israel)
EXAMPLE
For n = 3, 80 = 3^4 - 1^4 and 3*80 = 4^4 - 2^4.
MAPLE
T:= 10^12; N:= 100; # to get solutions with n*a(n)<=T and n <= N
cmax := floor(fsolve('c'^4 - ('c'-1)^4 = T));
S:= {seq(seq(c^4 - a^4, a = ceil((max(0, c^4 - T))^(1/4))..c-1), c=1..cmax)}:
for n from 1 to N do
B:= S intersect map(`*`, S, n);
if B <> {} then
A[n]:= min(B)/n;
printf("a[%d] = %d\n", n, A[n]);
end if
end do: # Robert Israel, Sep 02 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Sep 02 2013
STATUS
approved