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A256676 Digital roots of centered 11-gonal numbers (A069125). 1
1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3, 4, 7, 3, 1, 1, 3, 7, 4, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The sequence is periodic with period 9.

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

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

FORMULA

a(n) = A010888(A069125(n)).

a(n) = a(n-9).

G.f.: -x*(x^8+3*x^7+7*x^6+4*x^5+3*x^4+4*x^3+7*x^2+3*x+1) / ((x-1)*(x^2+x+1)*(x^6+x^3+1)).

EXAMPLE

a(3) = 7 because the 3rd centered 11-gonal number is 34, the digital root of which is 7.

MATHEMATICA

PadRight[{}, 100, {1, 3, 7, 4, 3, 4, 7, 3, 1}] (* Vincenzo Librandi, Apr 08 2015 *)

LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 1}, {1, 3, 7, 4, 3, 4, 7, 3, 1}, 86] (* Ray Chandler, Aug 26 2015 *)

PROG

(PARI) m=11; vector(200, n, (m*n*(n-1)/2)%9+1)

(MAGMA) &cat[[1, 3, 7, 4, 3, 4, 7, 3, 1]: n in [0..10] ]; // Vincenzo Librandi, Apr 08 2015

CROSSREFS

Cf. A010888, A069125.

Sequence in context: A197145 A163335 A266273 * A267412 A087941 A278389

Adjacent sequences:  A256673 A256674 A256675 * A256677 A256678 A256679

KEYWORD

nonn,base,easy

AUTHOR

Colin Barker, Apr 07 2015

STATUS

approved

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Last modified April 3 04:21 EDT 2020. Contains 333195 sequences. (Running on oeis4.)