A026992 a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026692.

1, 4, 15, 72, 385, 1740, 7200, 33892, 174369, 806288, 3477513, 16493280, 84033826, 393038584, 1732173866, 8260858904, 41899043017, 197360311690, 881681864213, 4220575766976, 21345258947469, 101030588041560, 455632655173002, 2186903113868104, 11036726477564350, 52421656397330054

Offset

1,2

Links

Table of n, a(n) for n=1..26.

Crossrefs

Sequence in context: A085349 A185133 A278640 * A039764 A171005 A303229

Adjacent sequences: A026989 A026990 A026991 * A026993 A026994 A026995

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Sean A. Irvine, Oct 21 2019

Status

approved