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

7, 47, 61, 103, 113, 211, 223, 229, 311, 337, 401, 419, 491, 787, 1021, 1453, 1489, 1697, 2039, 3659, 4703, 5279

Offset

1,1

Comments

Intersection of A018890 and A000040.

If, as is conjectured, the last term of A018890 is 8042, there are no more terms than those shown. - Robert Israel, Jul 14 2014

Links

Table of n, a(n) for n=1..22.

Example

a(1) = 7 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3.
a(2) = 47 = 3^3 + 2^3 + 2^3 + 1^3 + 1^3 + 1^3 + 1^3.
a(3) = 61 = 3^3 + 2^3 + 2^3 + 2^3 + 2^3 + 1^3 + 1^3.
a(4) = 103 = 4^3 + 3^3 + 2^3 + 1^3 + 1^3 + 1^3 + 1^3.

Maple

for n from 1 to 10^4 do
  m:= floor(n^(1/3));
  if m^3 = n then M[n]:= 1
  else
    M[n]:= 1 + min(seq(M[n-j^3], j=1..m));
  fi
od:
select(n -> M[n]=7 and isprime(n), [$1..10^4]); # Robert Israel, Jul 14 2014

Crossrefs

Cf. A000578, A018890, A000040.

Sequence in context: A124837 A122731 A059452 * A141882 A240569 A261183

Adjacent sequences: A245226 A245227 A245228 * A245230 A245231 A245232

Keyword

nonn,less,fini

Author

Rafael F. Farias, Jul 13 2014

Status

approved