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 A005941 Inverse of the Doudna sequence A005940. (Formerly M0510) 11
 1, 2, 3, 4, 5, 6, 9, 8, 7, 10, 17, 12, 33, 18, 11, 16, 65, 14, 129, 20, 19, 34, 257, 24, 13, 66, 15, 36, 513, 22, 1025, 32, 35, 130, 21, 28, 2049, 258, 67, 40, 4097, 38, 8193, 68, 23, 514, 16385, 48, 25, 26, 131, 132, 32769, 30, 37, 72, 259, 1026, 65537, 44, 131073, 2050, 39, 64 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(2^k) = 2^k. - _Robert G. Wilson v_, Feb 22 2005 Fixed points: A029747. - _Reinhard Zumkeller_, Aug 23 2006 REFERENCES J. H. Conway, personal communication. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS R. J. Mathar, Table of n, a(n) for n=1,..,5000 FORMULA a(n) = h(g(n,1,1), 0) / 2 + 1 with h(n, m) = if n=0 then m else h(floor(n/2), 2*m + n mod 2) and g(n, i, x) = if n=1 then x else (if n mod prime(i) = 0 then g(n/prime(i), i, 2*x+1) else g(n, i+1, 2*x). - _Reinhard Zumkeller_, Aug 23 2006 a(n) = 1 + A156552(n). - _Antti Karttunen_, Jun 26 2014 MAPLE (Maple code from _R. J. Mathar_, Mar 06 2010) f := proc(n, i, x) option remember ; if n = 0 then x; elif type(n, 'even') then procname(n/2, i+1, x) ; else procname((n-1)/2, i, x*ithprime(i)) ; end if; end proc: A005940 := proc(n) f(n-1, 1, 1) ; end proc: A005941 := proc(n) local k ; for k from 1 do if A005940(k) = n then return k; end if; end do ; end proc: MATHEMATICA f[n_] := Block[{p = Partition[ Split[ Join[ IntegerDigits[n - 1, 2], {2}]], 2]}, Times @@ Flatten[ Table[q = Take[p, -i]; Prime[ Count[ Flatten[q], 0] + 1]^q[[1, 1]], {i, Length[p]}] ]]; t = Table[ f[n], {n, 10^5}]; Flatten[ Table[ Position[t, n, 1, 1], {n, 64}]] (* _Robert G. Wilson v_, Feb 22 2005 *) PROG (Scheme) (define (A005941 n) (+ 1 (A156552 n))) ;; _Antti Karttunen_, Jun 26 2014 CROSSREFS Cf. A103969. Inverse of A005940. One more than A156552. Sequence in context: A324106 A252753 A005940 * A269857 A269847 A245705 Adjacent sequences:  A005938 A005939 A005940 * A005942 A005943 A005944 KEYWORD nonn AUTHOR _N. J. A. Sloane_ EXTENSIONS More terms from _Robert G. Wilson v_, Feb 22 2005 a(61) inserted by _R. J. Mathar_, Mar 06 2010 STATUS approved

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Last modified February 20 13:54 EST 2020. Contains 332078 sequences. (Running on oeis4.)