T(n,k)=Number of nXk 0..3 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.
A223406
T(n,k)=Number of nXk 0..3 arrays with all rows and columns having a nonnegative second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative.
Terms
- a(0) =4a(1) =16a(2) =16a(3) =36a(4) =256a(5) =36a(6) =150a(7) =1296a(8) =1296a(9) =150a(10) =558a(11) =22500a(12) =11254a(13) =22500a(14) =558a(15) =2126a(16) =311364a(17) =449810a(18) =449810a(19) =311364a(20) =2126a(21) =8480a(22) =4519876a(23) =13266784a(24) =75789786a(25) =13266784a(26) =4519876a(27) =8480a(28) =33639a(29) =71910400
External references
- oeis: A223406