A159371 Number of n X n arrays of squares of integers summing to 8.

6, 675, 34830, 1347525, 32145930, 460513662, 4464289944, 32292364770, 186464336850, 900743450145, 3764484413118, 13954005203463, 46750424936670, 143665627355100, 409707743053920, 1094582930018724, 2760817157366382

Offset: 2

Author

R. H. Hardin Apr 11 2009

Keywords

• nonn

Comments

All such sequences have holonomic recurrences (cf. comment in A159359). - Georg Fischer, Feb 17 2022

Links

• R. H. Hardin, Table of n, a(n) for n=2..100
• Index entries for linear recurrences with constant coefficients, signature (17, -136, 680, -2380, 6188, -12376, 19448, -24310, 24310, -19448, 12376, -6188, 2380, -680, 136, -17, 1).

Formula

Empirical: n^2*(n^2-1)*(n^12-27*n^10+295*n^8+15*n^6-10016*n^4+35652*^2-15120)/40320. [From R. J. Mathar, Aug 11 2009]