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A272530 Position of first occurrence of n in A072347. 2
0, 3, 7, 27, 15, 427, 55, 31, 215, 219, 111, 119, 63, 431, 443, 471, 439, 223, 239, 1879, 127, 1719, 863, 1755, 891, 887, 879, 3423, 447, 495, 479, 3451, 3447, 255, 3439, 3503, 1727, 27355, 1967, 1787, 1775, 14167, 1783, 1759, 1911, 1903, 895, 7855, 991, 959, 6907, 6895, 7087, 55983, 511, 7099, 6879, 14043, 7007, 3455 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) == 3 (mod 4) for n > 1, since A072347(2k) = A072347(floor(k/2)) and A072347(4k+1) = A072347(2k+1). - Robert Israel, May 04 2016

LINKS

Robert Israel and Alois P. Heinz, Table of n, a(n) for n = 1..10000 (first 3341 terms from Robert Israel)

Rémy Sigrist, Colored logarithmic scatterplot of a(n) for n = 1..10000 (where the color is function of the Hamming weight of a(n))

MAPLE

# using procedure a from A072347

R[1]:= 0:

for n from 3 to 100000 by 4 do

  v:= a(n);

  if not assigned(R[v]) then R[v]:= n

  fi

od:

for n from 1 while assigned(R[n]) do od:

seq(R[i], i=1..n-1); # Robert Israel, May 04 2016

MATHEMATICA

Block[{c, s}, c[w_] := With[{n = Length@ w}, Which[n == 0, 1, n == 1, First@ w, True, Last[w] c[Most@ w] + c[Most@ Most@ w]]]; s = {1}~Join~Array[c[IntegerDigits[#, 2]] &, 10^4]; TakeWhile[Array[-1 + FirstPosition[s, #][[1]] &, 50], IntegerQ]] (* Michael De Vlieger, Jan 20 2018, after Jean-François Alcover at A072347 *)

CROSSREFS

Cf. A072347.

Sequence in context: A305446 A334793 A175198 * A225038 A293564 A056257

Adjacent sequences:  A272527 A272528 A272529 * A272531 A272532 A272533

KEYWORD

nonn,look

AUTHOR

Jeffrey Shallit, May 02 2016

STATUS

approved

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Last modified May 17 19:47 EDT 2021. Contains 343988 sequences. (Running on oeis4.)