A281258 Digital root of n*(n+1)*(n+2)/2.

0, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9, 3, 3, 3, 6, 6, 6, 9, 9, 9

Offset: 0

Author

Peter M. Chema, Jan 18 2017

Keywords

• nonn
• base
• easy

Comments

Also zero together with period 9: repeat [3, 3, 3, 6, 6, 6, 9, 9, 9].

Also the decimal expansion of 334001/1001001.

Links

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

Crossrefs

Cf. A010888, A027480.

Programs

Mathematica

PadRight[{0},120,{9,3,3,3,6,6,6,9,9}] (* Harvey P. Dale, Mar 22 2018 *)

Formula

a(n) = A010888(A027480(n)).

From Stefano Spezia, Aug 30 2022: (Start)

G.f.: 3*x*(1 + 2*x^3 + 3*x^6)/((1 - x)*(1 + x^3 + x^6)).

a(n) = a(n-1) - a(n-3) + a(n-4) - a(n-6) + a(n-7) for n > 7. (End)