A091760 0^n+3((n+2)^n/(n+3)-(-1)^n/(n+3)).

1, 3, 9, 63, 555, 6303, 87381, 1434891, 27272727, 589486923, 14288622513, 384034370151, 11338782475059, 364911575317383, 12716046006693165, 477070508584969299, 19174662804725408175, 822058028667720327891

Offset: 0

Author

Paul Barry, Feb 03 2004

Keywords

• easy
• nonn

Crossrefs

Cf. A083063.