cp's OEIS Frontend

A245229 Primes that are the sum of 7 cubes and no fewer.

%I A245229 #20 Jul 20 2014 16:42:19
%S A245229 7,47,61,103,113,211,223,229,311,337,401,419,491,787,1021,1453,1489,
%T A245229 1697,2039,3659,4703,5279
%N A245229 Primes that are the sum of 7 cubes and no fewer.
%C A245229 Intersection of A018890 and A000040.
%C A245229 If, as is conjectured, the last term of A018890 is 8042, there are no more terms than those shown. - _Robert Israel_, Jul 14 2014
%e A245229 a(1) = 7 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3.
%e A245229 a(2) = 47 = 3^3 + 2^3 + 2^3 + 1^3 + 1^3 + 1^3 + 1^3.
%e A245229 a(3) = 61 = 3^3 + 2^3 + 2^3 + 2^3 + 2^3 + 1^3 + 1^3.
%e A245229 a(4) = 103 = 4^3 + 3^3 + 2^3 + 1^3 + 1^3 + 1^3 + 1^3.
%p A245229 for n from 1 to 10^4 do
%p A245229   m:= floor(n^(1/3));
%p A245229   if m^3 = n then M[n]:= 1
%p A245229   else
%p A245229     M[n]:= 1 + min(seq(M[n-j^3],j=1..m));
%p A245229   fi
%p A245229 od:
%p A245229 select(n -> M[n]=7 and isprime(n), [$1..10^4]); # _Robert Israel_, Jul 14 2014
%Y A245229 Cf. A000578, A018890, A000040.
%K A245229 nonn,less,fini
%O A245229 1,1
%A A245229 _Rafael F. Farias_, Jul 13 2014