A378384 Contribution to the OEIS

 A378384

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

0

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

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OFFSET

0,4

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

Table of n, a(n) for n=0..87.

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).

FORMULA

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

MATHEMATICA

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

CROSSREFS

Cf. A000213, A010888, A112661.

Sequence in context: A221967 A079428 A094548 * A112661 A230725 A254689

Adjacent sequences: A378381 A378382 A378383 * A378386 A378388 A378389

KEYWORD

nonn,base,easy,new

AUTHOR

James C. McMahon, Nov 24 2024

STATUS

approved