A327294 - OEIS

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A327294

a(n) = (A325907(n) + 1) * (10^(2^(n-1)) - A325907(n)).

28, 2368, 22326868, 2222332366866868, 22222222333322326666886866866868, 2222222222222222333333332222332366666666888866866666886866866868

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

a(n) is composed of digits {2,3,6,8}.

LINKS

Table of n, a(n) for n=1..6.

FORMULA

a(n) = 2 * (10^(2^n) + 3 * 10^(2^(n-1)) - 4)/9 - 2 * A325493(n-1) + A325910(n-1) * 10^(2^(n-1)).

EXAMPLE

a(1) = 2 * 10^1 + 8.

a(2) = 23 * 10^2 + 68.

a(3) = 2232 * 10^4 + 6868.

a(4) = 22223323 * 10^8 + 66866868.

a(5) = 2222222233332232 * 10^16 + 6666886866866868.

And

2 = 2 * (10^1 - 1)/9 + 0.

23 = 2 * (10^2 - 1)/9 + 1.

2232 = 2 * (10^4 - 1)/9 + 10.

22223323 = 2 * (10^8 - 1)/9 + 1101.

2222222233332232 = 2 * (10^16 - 1)/9 + 11110010.

And

8 = 8 * (10^1 - 1)/9 - 2 * 0.

68 = 8 * (10^2 - 1)/9 - 2 * 10.

6868 = 8 * (10^4 - 1)/9 - 2 * 1010.

66866868 = 8 * (10^8 - 1)/9 - 2 * 11011010.

6666886866866868 = 8 * (10^16 - 1)/9 - 2 * 1111001011011010.

PROG

(Ruby)

def A(n)

a = [3, 6]

b = ([[3]] + (1..n - 1).map{|i| [a[i % 2]] * (2 ** (i - 1))}).reverse.join.to_i

(b + 1) * (10 ** (2 ** (n - 1)) - b)

end

def A327294(n)

(1..n).map{|i| A(i)}

end

p A327294(6)

CROSSREFS

Cf. A325907, A325910, A325493, A327266.

Sequence in context: A203751 A178187 A184134 * A281137 A100548 A103660

Adjacent sequences: A327291 A327292 A327293 * A327295 A327296 A327297

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Sep 16 2019

STATUS

approved