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A167873 Period 4: repeat [10, 6, 10, 4]. 2
10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4, 10, 6, 10, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Number of different remainders mod 10 of n-th powers (i.e., number of possible last decimal digits of n-th powers).

Continued fraction expansion of (124+sqrt(16926))/25. - Klaus Brockhaus, May 01 2010

LINKS

Muniru A Asiru, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = 8 - 4*((n+1) mod 2) + 2*ceiling(n/4) - 2*floor(n/4). - Wesley Ivan Hurt, Mar 26 2014

a(n) = 15/2 - (5/2)*cos(n*Pi) - cos(n*Pi/2). - Wesley Ivan Hurt, Oct 05 2018

EXAMPLE

a(4) = 4 because the possible last decimal digits of 4th powers are 0, 1, 5, 6.

MAPLE

seq(op([10, 6, 10, 4]), n=0..30); # Wesley Ivan Hurt, Oct 06 2018

MATHEMATICA

PadRight[{}, 80, {10, 6, 10, 4}] (* Harvey P. Dale, Nov 29 2015 *)

PROG

(GAP) Flat(List([1..30], n->[10, 6, 10, 4])); # Muniru A Asiru, Oct 06 2018

CROSSREFS

Cf. A177015 (decimal expansion of (124+sqrt(16926))/25). - Klaus Brockhaus, May 01 2010

Sequence in context: A105155 A072930 A071358 * A033986 A049004 A104645

Adjacent sequences:  A167870 A167871 A167872 * A167874 A167875 A167876

KEYWORD

easy,nonn

AUTHOR

Franz Vrabec, Nov 14 2009

STATUS

approved

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Last modified October 22 15:09 EDT 2021. Contains 348171 sequences. (Running on oeis4.)