A027240 a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026769.

1, 4, 19, 80, 391, 1738, 8797, 40878, 212491, 1023392, 5426518, 26891674, 144717381, 733600690, 3991767587, 20603079346, 113049604075, 591971513924, 3269119157724, 17319091807608, 96127613360983, 514139933872914, 2865265217457906, 15446276427044382, 86367699910234830

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Extensions

More terms from Sean A. Irvine, Oct 26 2019