A114957 a(n) = ceiling(a(n-1)^(4/3) + a(n-2)^(4/3)), with a(0) = a(1) = 1.

1, 1, 2, 4, 9, 26, 96, 517, 4589, 80409, 3546873, 544383737, 445042712531, 3398279290987133, 510914600201184438040, 4084427005585662985398294639, 6528922582874884079540382952631569851, 12202683821888699966029264978793346242448495941305

Offset: 0

Author

Jonathan Vos Post, Feb 21 2006

Keywords

• easy
• nonn

Examples

			a(2) = ceiling(a(0)^(4/3) + a(1)^(4/3)) = ceiling(1^(4/3) + 1^(4/3)) = 2.
a(3) = ceiling(a(1)^(4/3) + a(2)^(4/3)) = ceiling(1^(4/3) + 2^(4/3)) = ceiling(3.5198421) = 4.
a(4) = ceiling(2^(4/3) + 4^(4/3)) = ceiling(8.86944631) = 9.
a(5) = ceiling(4^(4/3) + 9^(4/3)) = ceiling(25.0703586) = 26.
a(6) = ceiling(9^(4/3) + 26^(4/3)) = ceiling(95.7456522) = 96.
a(7) = ceiling(26^(4/3) + 96^(4/3)) = ceiling(516.595167) = 517.
a(8) = ceiling(96^(4/3) + 517^(4/3)) = ceiling(4588.99022) = 4589.
		

Crossrefs

Cf. A000283, A112961, A112969, A114793.

Programs

Mathematica

Nest[Append[#,Ceiling[Total[Take[#,-2]^(4/3)]]]&,{1,1},17]  (* Harvey P. Dale, Apr 21 2011 *)

Extensions

Corrected and extended by Harvey P. Dale, Apr 21 2011

Comments edited by Petros Hadjicostas, Nov 03 2019