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A004167 Powers of 3 written backwards. 16
1, 3, 9, 72, 18, 342, 927, 7812, 1656, 38691, 94095, 741771, 144135, 3234951, 9692874, 70984341, 12764034, 361041921, 984024783, 7641622611, 1044876843, 30235306401, 90695018313, 72887134149, 184635924282, 344906882748, 9238285681452, 7894847955267 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

From a(2) onwards, all terms are divisible by 9. - Alonso del Arte, Apr 04 2014

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = A004086(A000244(n)). - Michel Marcus, Apr 05 2014

EXAMPLE

a(5) = 342 since 3^5 = 243.

MAPLE

a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(3^n)):

seq(a(n), n=0..50); # Alois P. Heinz, Apr 09 2015

MATHEMATICA

Table[FromDigits[Reverse[IntegerDigits[3^n]]], {n, 0, 26}] (* Alonso del Arte, Apr 04 2014 *)

PROG

(Python)

def A004167(n):

return int(str(3**n)[::-1]) # Chai Wah Wu, Feb 19 2021

CROSSREFS

The following are parallel families: A000079 (2^n), A004094 (2^n reversed), A028909 (2^n sorted up), A028910 (2^n sorted down), A036447 (double and reverse), A057615 (double and sort up), A263451 (double and sort down); A000244 (3^n), A004167 (3^n reversed), A321540 (3^n sorted up), A321539 (3^n sorted down), A163632 (triple and reverse), A321542 (triple and sort up), A321541 (triple and sort down).

Sequence in context: A084543 A318030 A018564 * A321539 A163632 A321541

Adjacent sequences: A004164 A004165 A004166 * A004168 A004169 A004170

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Eric M. Schmidt, Apr 04 2014

STATUS

approved

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Last modified December 3 11:24 EST 2022. Contains 358517 sequences. (Running on oeis4.)