OFFSET
1,3
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
E.g. 15=2^4-1^4, 175=4^4-3^4
MATHEMATICA
Select[Abs[Differences/@Tuples[Range[0, 12]^4, 2]]//Flatten//Union, #<= 6500&] (* Harvey P. Dale, Sep 14 2020 *)
PROG
(PARI) is(n)=if(n<1, return(!n)); for(m=sqrtnint(n-1, 4)+1, sqrtnint(n\4, 3)+1, if(ispower(m^4-n, 4), return(1))); 0 \\ Charles R Greathouse IV, Sep 04 2013
(PARI) lst(lim)=my(v=List([0]), t); lim\=1; for(n=1, sqrtnint(lim\4, 3)+1, for(m=sqrtnint(max(n^4-lim, 0), 4), n-1, t=n^4-m^4; if(t<=lim, listput(v, t)))); vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, Sep 04 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Mark Taggart (mt2612f(AT)aol.com), Nov 21 2008
EXTENSIONS
Extended by Ray Chandler, Dec 04 2008
Definition corrected by Harvey P. Dale, Jan 19 2018
STATUS
approved