OFFSET
1,1
COMMENTS
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..621 from R. J. Mathar)
MAPLE
isA030078 := proc(n)
local f ;
if n < 8 then
false;
else
f := ifactors(n)[2] ;
if nops(f) = 1 and op(2, op(1, f)) = 3 then
true;
else
false;
end if;
end if;
end proc:
isA138854 := proc(n)
local i, j, p, q, r, rcub ;
for i from 1 do
p := ithprime(i) ;
if p^3+(p+1)^3+(p+2)^3 > n then
return false;
end if;
for j from i+1 do
q := ithprime(j) ;
rcub := n-q^3-p^3 ;
if rcub <= q^3 then
break;
fi ;
if isA030078(rcub) then
return true;
end if;
end do:
end do:
end proc:
for n from 5 do
if isA138854(n) then
print(n);
end if;
end do: # R. J. Mathar, Jun 09 2014
MATHEMATICA
f[upto_]:=Module[{maxp=PrimePi[Floor[Power[upto, (3)^-1]]]}, Select[Union[Total/@(Subsets[Prime[Range[maxp]], {3}]^3)], #<=upto&]]; f[9000] (* Harvey P. Dale, Mar 21 2011 *)
PROG
(PARI) isA138854(n)={ if( n%2, isA138853(n), isA120398(n-8)) }
for( n=1, 10^4, isA138854(n) & print1(n", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Apr 13 2008
STATUS
approved