A378384 Digital root of the sum of the previous 3 terms; a(0) = a(1) = a(2) = 1.

1, 1, 1, 3, 5, 9, 8, 4, 3, 6, 4, 4, 5, 4, 4, 4, 3, 2, 9, 5, 7, 3, 6, 7, 7, 2, 7, 7, 7, 3, 8, 9, 2, 1, 3, 6, 1, 1, 8, 1, 1, 1, 3, 5, 9, 8, 4, 3, 6, 4, 4, 5, 4, 4, 4, 3, 2, 9, 5, 7, 3, 6, 7, 7, 2, 7, 7, 7, 3, 8, 9, 2, 1, 3, 6, 1, 1, 8, 1, 1, 1, 3, 5, 9, 8, 4, 3, 6

Offset: 0

Author

James C. McMahon, Nov 24 2024

Keywords

• nonn
• base
• easy

Comments

This differs from A112661 which is sum of digits of sum of previous 3 terms.

Digital root of A000213 (tribonacci numbers beginning {1,1,1}).

This has a period of 39 beginning with the first term.

Decimal expansion of 12373315960504936995263080863765792902/111111111111111111111111111111111111111 = 0.[111359843644544432957367727773892136118] (periodic).

Links

• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).

Crossrefs

Cf. A000213, A010888, A112661.

Programs

Mathematica

Nest[Append[#,ResourceFunction["AdditiveDigitalRoot"][Total[Take[#,-3]]]]&,{1,1,1},85]

Formula

a(n) = A010888(A000213(n)).