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%I #24 Jan 03 2020 04:34:20
%S 1,2,4,8,61,221,244,884,8671,24371,24784,86594,881371,2472671,2435494,
%T 8890784,86518771,245730371,247064194,883821494,8892467671,
%U 24353948771,24579870784,86514795194,883095920371,2470481916671,2433383690494
%N Double and reverse digits.
%H Harvey P. Dale, <a href="/A036447/b036447.txt">Table of n, a(n) for n = 0..1000</a>
%H Nick Hobson, <a href="/A036447/a036447.py.txt">Python program for this sequence</a>
%F a(n+1) = A004093(a(n)). - _Reinhard Zumkeller_, Feb 09 2012
%F Conjecture: a(n)^(1/n) tends to sqrt(10). - _Vaclav Kotesovec_, Jan 03 2020
%t NestList[ FromDigits[ Reverse[ IntegerDigits[ 2# ] ] ] &, 1, 27 ]
%t NestList[IntegerReverse[2#]&,1,30] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 18 2017 *)
%o (Haskell)
%o a036447 n = a036447_list !! n
%o a036447_list = iterate a004093 1 -- _Reinhard Zumkeller_, Feb 09 2012
%Y Cf. A004086, A004093.
%Y 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).
%Y Cf. A132064, A045539, A132078, A132114, A132113, A133361.
%K nonn,base,easy,nice
%O 0,2
%A _Rodolfo Kurchan_
%E More terms from Larry Reeves (larryr(AT)acm.org), Mar 31 2000
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