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A321542 a(0)=1; thereafter a(n) = 3*a(n-1) with digits rearranged into non-decreasing order. 14
1, 3, 9, 27, 18, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

For n >= 5, alternates between 45 and 135.

LINKS

Table of n, a(n) for n=0..52.

FORMULA

G.f.: (-117*x^6 - 18*x^5 - 9*x^4 - 24*x^3 - 8*x^2 - 3*x - 1)/(x^2 - 1). - Chai Wah Wu, Nov 20 2018

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: A131997 A122842 A070358 * A321540 A036123 A168427

Adjacent sequences:  A321539 A321540 A321541 * A321543 A321544 A321545

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Nov 19 2018

STATUS

approved

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Last modified March 19 13:25 EDT 2019. Contains 321330 sequences. (Running on oeis4.)