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 A036447 Double and reverse digits. 20
 1, 2, 4, 8, 61, 221, 244, 884, 8671, 24371, 24784, 86594, 881371, 2472671, 2435494, 8890784, 86518771, 245730371, 247064194, 883821494, 8892467671, 24353948771, 24579870784, 86514795194, 883095920371, 2470481916671, 2433383690494 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000 Nick Hobson, Python program for this sequence FORMULA a(n+1) = A004093(a(n)). - Reinhard Zumkeller, Feb 09 2012 Conjecture: a(n)^(1/n) tends to sqrt(10). - Vaclav Kotesovec, Jan 03 2020 MATHEMATICA NestList[ FromDigits[ Reverse[ IntegerDigits[ 2# ] ] ] &, 1, 27 ] NestList[IntegerReverse[2#]&, 1, 30] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 18 2017 *) PROG (Haskell) a036447 n = a036447_list !! n a036447_list = iterate a004093 1 -- Reinhard Zumkeller, Feb 09 2012 CROSSREFS Cf. A004086, A004093. 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). Cf. A132064, A045539, A132078, A132114, A132113, A133361. Sequence in context: A004094 A028910 A018482 * A263451 A339951 A069027 Adjacent sequences: A036444 A036445 A036446 * A036448 A036449 A036450 KEYWORD nonn,base,easy,nice AUTHOR EXTENSIONS More terms from Larry Reeves (larryr(AT)acm.org), Mar 31 2000 STATUS approved

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Last modified December 9 19:36 EST 2022. Contains 358703 sequences. (Running on oeis4.)