OFFSET
1,2
COMMENTS
LINKS
Eric Weisstein's World of Mathematics, Waring's Problem.
FORMULA
a(n) = binomial(b(x/2)+1, 2) + (Sum_{a=b(x/2)+1..b(x)} b(x-a^4)) - Sum_{m in A018786, m<=x} (A216284(m) - 1), where b(t) = floor(t^(1/4)) and x = 10^n - 1. - Martin Fuller, Jan 01 2026
MAPLE
isbiquadrate:=proc(n) type(root(n, 4), posint); end:
isA003336:=proc(n) local x, y4; if isbiquadrate(n) then false; else for x from 1 do y4:=n-x^4; if y4<x^4 then return false; elif isbiquadrate(y4) then return true; fi; od; fi; end:
a:=proc(n) local i, k; i:=0; for k from 2 to 10^n-1 do if isA003336(k) then i:=i+1; fi; od: return(i); end: for n from 1 do print(a(n)); od;
CROSSREFS
KEYWORD
nonn
AUTHOR
Martin Renner, Feb 25 2011
EXTENSIONS
a(6) from Martin Renner, Feb 26 2011
a(7)-a(16) from Lars Blomberg, May 08 2011
a(17)-a(24) from Martin Fuller, Jan 01 2026
a(25)-a(28) from A003824 by Martin Fuller, Feb 01 2026
STATUS
approved