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A071542
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Number of steps to reach 0 starting with n and using the iterated process : x -> x - (number of 1's in binary representation of x).
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25
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0, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 22, 22, 23, 23, 24, 24, 24, 24, 25, 25, 25, 25
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OFFSET
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0,3
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LINKS
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FORMULA
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It seems that a(n) ~ C n/log(n) asymptotically with C = 1.4... (n = 10^6 gives C = 1.469..., n = 10^7 gives C = 1.4614...).
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EXAMPLE
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17 (= 10001 in binary) -> 15 (= 1111) -> 11 (= 1011) -> 8 (= 1000) -> 7 (= 111) -> 4 (= 100) -> 3 (= 11) -> 1 -> 0, hence a(17)=8.
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MATHEMATICA
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Table[-1 + Length@ NestWhileList[# - DigitCount[#, 2, 1] &, n, # > 0 &], {n, 0, 75}] (* Michael De Vlieger, Jul 16 2017 *)
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PROG
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(PARI) for(n=1, 150, s=n; t=0; while(s!=0, t++; s=s-sum(i=1, length(binary(s)), component(binary(s), i))); if(s==0, print1(t, ", "); ); )
(MIT/GNU Scheme)
;; with memoizing definec-macro:
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CROSSREFS
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A179016 gives the unique infinite sequence whose successive terms are related by this iterated process (in reverse order). Also, it seems that for n>=0, a(A213708(n) = a(A179016(n+1)) = n.
A213709(n) = a((2^(n+1))-1) - a((2^n)-1).
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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Starting offset changed to 0 with a(0) prepended as 0 by Antti Karttunen, Oct 24 2012
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STATUS
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approved
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