A074364 Semi-tribonacci numbers, from tribonacci by analogy with semi-Fibonacci sequence.

0, 1, 1, 2, 1, 4, 2, 7, 1, 10, 4, 15, 2, 21, 7, 30, 1, 38, 10, 49, 4, 63, 15, 82, 2, 99, 21, 122, 7, 150, 30, 187, 1, 218, 38, 257, 10, 305, 49, 364, 4, 417, 63, 484, 15, 562, 82, 659, 2, 743, 99, 844, 21, 964, 122, 1107, 7, 1236, 150, 1393, 30, 1573, 187, 1790, 1, 1978, 218

Offset: 0

Author

Michael Joseph Halm, Feb 13 2003

Keywords

• nonn

Examples

			a(4)=1 because a(4/2)=a(2)=1.
		

Links

• T. D. Noe, Table of n, a(n) for n = 0..10000
• Cristina Ballantine and George Beck, Partitions enumerated by self-similar sequences, arXiv:2303.11493 [math.CO], 2023.
• M. J. Halm, Sequences

Crossrefs

Cf. A030067, A000073.

Formula

a(0) = 0, a(1) = 1, a(2n) = a(n), a(2n+1) = a(2n)+a(2n-1)+a(2n-2)