A261143 a(n) = H_n(1,2) where H_n is the n-th hyperoperator.

3, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

Offset: 0

Author

Natan Arie Consigli, Aug 24 2015

Keywords

• nonn
• cons
• easy

Comments

See A054871 for definitions and key links.

Sequence is also the decimal expansion of 2989/9000.

Examples

			a(0) = H_0(1,2) = 2+1 = 3;
a(1) = H_1(1,2) = 1+2 = 3;
a(2) = H_2(1,2) = 1*2 = 2;
a(3) = H_3(1,2) = 1^2 = 1;
a(4) = H_4(1,2) = 1^^2 = 1.
		

Links

• Dominika Závacká, Cristina Dalfó, and Miquel Angel Fiol, Integer sequences from k-iterated line digraphs, CEUR: Proc. 24th Conf. Info. Tech. - Appl. and Theory (ITAT 2024) Vol 3792, 156-161. See p. 161, Table 2.
• Index entries for linear recurrences with constant coefficients, signature (1).

Crossrefs

Cf. A054871.

Formula

From Elmo R. Oliveira, Jul 16 2024: (Start)

G.f.: (3-x^2-x^3)/(1-x).

a(n) = 1 for n >= 3. (End)

E.g.f.: exp(x) + 2 + 2*x + x^2/2. - Elmo R. Oliveira, Aug 09 2024