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 A030102 Base-3 reversal of n (written in base 10). 33
 0, 1, 2, 1, 4, 7, 2, 5, 8, 1, 10, 19, 4, 13, 22, 7, 16, 25, 2, 11, 20, 5, 14, 23, 8, 17, 26, 1, 28, 55, 10, 37, 64, 19, 46, 73, 4, 31, 58, 13, 40, 67, 22, 49, 76, 7, 34, 61, 16, 43, 70, 25, 52, 79, 2, 29, 56, 11, 38, 65, 20, 47, 74, 5, 32, 59, 14, 41, 68, 23, 50, 77, 8, 35, 62, 17, 44, 71 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..10000 Michael Gilleland, Some Self-Similar Integer Sequences Lukas Spiegelhofer, A digit reversal property for an analogue of Stern's sequence, arXiv:1709.05651 [math.NT], 2017. See Theorem 1.1. FORMULA a(n) = t(n,0) with t(n,r) = if n=0 then r else t(floor(n/3),r*3+(n mod 3)). - Reinhard Zumkeller, Mar 04 2010 G.f. G(x) satisfies: G(x) = (1+x+x^2)*G(x^3) - (1+2*x)*(x + 2*Sum_{m>=0} 3^m*x^(3^(m+1)+1)/(x^3-1). - Robert Israel, Dec 24 2015 EXAMPLE a(17) = 25 because 17 in base 3 is 122, and backwards that is 221, which is 25 in base 10. a(18) = 2 because 18 in base 3 is 200, and backwards that is 2. MAPLE a030102:= proc(n) option remember;   local y;   y:= n mod 3;   3^ilog[3](n)*y + procname((n-y)/3) end proc: for i from 0 to 2 do a030102(i):= i od: seq(a030102(i), i=0..100); # Robert Israel, Dec 24 2015 # alternative A030102 := proc(n)     local r ;     r := ListTools[Reverse](convert(n, base, 3)) ;     add(op(i, r)*3^(i-1), i=1..nops(r)) ; end proc: # R. J. Mathar, May 28 2016 MATHEMATICA A030102[n_] := FromDigits[Reverse@IntegerDigits[n, 3], 3] (* JungHwan Min, Dec 23 2015 *) FromDigits[#, 3]&/@(Reverse/@IntegerDigits[Range[0, 80], 3]) (* Harvey P. Dale, Feb 05 2020 *) PROG (PARI) a(n, b=3)=subst(Polrev(base(n, b)), x, b)) /* where */ base(n, b)={my(a=[n%b]); while(0 3 * v + d) 0 . a030341_row -- Reinhard Zumkeller, Dec 16 2013 CROSSREFS Cf. A134028, A030101 - A030108, A004086, A134028. Cf. A030341. Cf. A263273 for a bijective variant. Sequence in context: A091320 A225468 A048787 * A072010 A255588 A328034 Adjacent sequences:  A030099 A030100 A030101 * A030103 A030104 A030105 KEYWORD nonn,base,look AUTHOR STATUS approved

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Last modified September 20 10:49 EDT 2020. Contains 337264 sequences. (Running on oeis4.)