A159405 Number of n X n arrays of squares of integers summing to 20.

18, 7326, 2995908, 1455763635, 622097389872, 206307703531587, 47588288640846912, 7046841590377578801, 653092799056599247740, 39121901776525814650965, 1603648230996545513760708, 47634024309523287458232228, 1076943060410127149424142230

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
• Vaclav Kotesovec, G.f. for A159405
• Index entries for linear recurrences with constant coefficients, signature (41, -820, 10660, -101270, 749398, -4496388, 22481940, -95548245, 350343565, -1121099408, 3159461968, -7898654920, 17620076360, -35240152720, 63432274896, -103077446706, 151584480450, -202112640600, 244662670200, -269128937220, 269128937220, -244662670200, 202112640600, -151584480450, 103077446706, -63432274896, 35240152720, -17620076360, 7898654920, -3159461968, 1121099408, -350343565, 95548245, -22481940, 4496388, -749398, 101270, -10660, 820, -41, 1).

Formula

G.f.: see link above. - Vaclav Kotesovec, Dec 04 2012