A014393 - OEIS

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A014393

Final 2 digits of 9^n.

1, 9, 81, 29, 61, 49, 41, 69, 21, 89, 1, 9, 81, 29, 61, 49, 41, 69, 21, 89, 1, 9, 81, 29, 61, 49, 41, 69, 21, 89, 1, 9, 81, 29, 61, 49, 41, 69, 21, 89, 1, 9, 81, 29, 61, 49, 41, 69, 21, 89, 1, 9, 81, 29, 61, 49, 41, 69, 21, 89

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OFFSET

0,2

COMMENTS

Period is 10, i.e., a(n+10) = a(n). - Martin Renner, Jun 11 2020

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for sequences related to final digits of numbers

FORMULA

a(n) = 9^n mod 100. - Martin Renner, Jun 11 2020

MAPLE

seq(9^n mod 100, n=0..80); # Martin Renner, Jun 11 2020

MATHEMATICA

Flatten[Prepend[FromDigits[Take[IntegerDigits[#], -2]]&/@(9^Range[2, 60]), {1, 9}]] (* Harvey P. Dale, Jan 22 2011 *)

PowerMod[9, Range[0, 80], 100] (* Vincenzo Librandi, Aug 16 2016 *)

PROG

(Magma) [Modexp(9, n, 100): n in [0..110]]; // Vincenzo Librandi, Aug 16 2016

(PARI) a(n) = lift(Mod(9, 100)^n); \\ Michel Marcus, Aug 16 2016

CROSSREFS

Cf. A001019 (9^n), A010690 (final digit of 9^n).

Sequence in context: A219664 A107346 A209280 * A008463 A203656 A043087

Adjacent sequences: A014390 A014391 A014392 * A014394 A014395 A014396

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane

STATUS

approved