A159389 Number of n X n arrays of squares of integers summing to 13.

16, 1962, 350240, 48299450, 5030081280, 346589305664, 14664677168512, 394240010602320, 7283982145272800, 99396267512446410, 1059813625787601696, 9216296747192215226, 67545604711093622960, 427985285624487838800

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 (27, -351, 2925, -17550, 80730, -296010, 888030, -2220075, 4686825, -8436285, 13037895, -17383860, 20058300, -20058300, 17383860, -13037895, 8436285, -4686825, 2220075, -888030, 296010, -80730, 17550, -2925, 351, -27, 1).

Formula

Empirical G.f.: -2*x^2*(1+x)*(8 + 757*x + 150684*x^2 + 19591732*x^3 + 1902144428*x^4 + 111467309309*x^5 + 3357053495448*x^6 + 49669712820552*x^7 + 379085540031904*x^8 + 1572597871783886*x^9 + 3663335172842872*x^10 + 4854870652776840*x^11 + 3663335172842872*x^12 + 1572597871783886*x^13 + 379085540031904*x^14 + 49669712820552*x^15 + 3357053495448*x^16 + 111467309309*x^17 + 1902144428*x^18 + 19591732*x^19 + 150684*x^20 + 757*x^21 + 8*x^22)/(-1+x)^27. - Vaclav Kotesovec, Nov 30 2012