A027258 a(n) = Sum_{k=0..2n-1} T(n,k) * T(n,k+1), with T given by A025177.

0, 6, 52, 428, 3552, 29790, 251980, 2145822, 18373296, 158025186, 1364247180, 11815188000, 102606325136, 893175905778, 7791151047204, 68086757974300, 595980599148672, 5224392846601730, 45857525238248604, 402997448078904948, 3545390129177031520, 31221592914677352138

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Extensions

a(1) corrected and more terms from Sean A. Irvine, Oct 26 2019