A347669 - OEIS

A347669

Indices of first occurrences of n in A347409.

1, 2, 4, 8, 3, 15, 21, 128, 75, 512, 151, 2048, 1365, 8192, 5461, 7407, 14563, 131072, 87381, 524288, 184111, 2097152, 932067, 6213783, 5592405, 33554432, 13256071, 134217728, 26512143, 530242875, 357913941, 1899273247, 1431655765, 8589934592, 3817748707, 34359738368

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..35.

Index entries for sequences related to 3x+1 (or Collatz) problem

EXAMPLE

a(5) = 15 because 5 occurs for the first time at position 15 in A347409.

MATHEMATICA

A347409[n_]:=A347409[n]=(c=n; sm=0; While[c>1, If[OddQ[c], c=3c+1, If[(s=IntegerExponent[c, 2])>sm, sm=s]; c/=2^s]]; sm)

nterms=20; Table[i=0; While[A347409[++i]!=n]; i, {n, 0, nterms-1}]

PROG