A027288 a(n) = Sum_{k=0..floor(n/2)} T(n,k) * T(n,k+1), with T given by A026009.

1, 4, 12, 46, 145, 552, 1820, 6918, 23562, 89645, 312664, 1191885, 4232345, 16170728, 58229100, 222997812, 811985790, 3116622123, 11451785640, 44047806725, 163072988442, 628465576101, 2341484487832, 9040083756276, 33863310322100, 130957152428622

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Extensions

More terms from Sean A. Irvine, Oct 26 2019