A027154 a(n) = Sum_{k=0..floor(n/2)} A027144(n-k, k).

1, 1, 3, 5, 9, 15, 31, 49, 101, 163, 331, 533, 1089, 1751, 3575, 5753, 11741, 18891, 38563, 62045, 126649, 203775, 415951, 669249, 1366101, 2198003, 4486651, 7218853, 14735409, 23708711, 48395175, 77865993, 158943181, 255733531, 522013523, 839899885, 1714437289, 2758464335

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Formula

Conjectures from Chai Wah Wu, Jun 10 2025: (Start)

a(n) = 2*a(n-2) + 3*a(n-4) + 4*a(n-6) for n > 5.

G.f.: -(x^2 + 1)*(2*x^3 + x + 1)/(4*x^6 + 3*x^4 + 2*x^2 - 1). (End)

Extensions

More terms from Sean A. Irvine, Oct 24 2019