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

1,2

Links

Table of n, a(n) for n=1..25.

Crossrefs

Sequence in context: A122909 A215037 A181300 * A326649 A050914 A017961

Adjacent sequences: A027237 A027238 A027239 * A027241 A027242 A027243

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Sean A. Irvine, Oct 26 2019

Status

approved