A193243 Number of representations of n as sum of three positive biquadrates, i.e., fourth powers.

0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1

Offset

0

Links

M. F. Hasler, Table of n, a(n) for n = 0..30000

Example

a(18) = 1 because there is only one way to represent 18 as a sum of fourth powers: 1^4 + 1^4 + 2^4.

Prog

(PARI) A193243(n)=sum(i=1, sqrtn(n\3, 4), if(isA000404(n-i^4), sum(j=i, sqrtn((n-i^4)\2, 4), ispower(n-i^4-j^4, 4))))

Crossrefs

Cf. A003337 (lists indices of nonzero terms), A193244 (indices of terms > 1).

Sequence in context: A130543 A185013 A346459 * A281302 A369426 A340599

Adjacent sequences: A193240 A193241 A193242 * A193244 A193245 A193246

Keyword

nonn

Author

M. F. Hasler, Dec 31 2012

Status

approved