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A166923 Digital root of prime(n)^2. 3
4, 9, 7, 4, 4, 7, 1, 1, 7, 4, 7, 1, 7, 4, 4, 1, 7, 4, 7, 1, 1, 4, 4, 1, 4, 4, 7, 1, 1, 7, 1, 7, 4, 7, 7, 4, 7, 1, 7, 4, 1, 1, 4, 7, 1, 1, 7, 4, 4, 7, 1, 7, 4, 1, 7, 4, 1, 1, 4, 4, 7, 7, 1, 7, 4, 4, 4, 7, 7, 4, 4, 1, 4, 7, 1, 7, 4, 1, 7, 7, 7, 4, 1, 1, 4, 4, 1, 4, 4, 7, 1, 4, 1, 7, 7, 1, 7, 1, 1, 1, 4, 1, 7, 4, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

MATHEMATICA

Table[If[(m9=Mod[Prime[n]^2, 9])==0, 9, m9], {n, 200}]

PROG

(Python)

from sympy import prime

def A166923(n):

....return 1 + (prime(n)**2-1) % 9 # Chai Wah Wu, Sep 03 2014

CROSSREFS

Cf. A010888, A038194.

Sequence in context: A021909 A018880 A245670 * A021205 A296425 A306004

Adjacent sequences:  A166920 A166921 A166922 * A166924 A166925 A166926

KEYWORD

base,nonn

AUTHOR

Zak Seidov, Oct 23 2009

EXTENSIONS

Definition corrected by Chai Wah Wu, Sep 03 2014

STATUS

approved

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Last modified October 18 18:10 EDT 2018. Contains 316323 sequences. (Running on oeis4.)