A222753 - OEIS

A222753

Number of odd numbers k such that difference between halving and tripling steps in Collatz (3x+1) trajectory of k is n.

1, 0, 0, 2, 0, 2, 3, 6, 6, 9, 11, 19, 28, 43, 66, 98, 145, 219, 327, 474, 744, 1125, 1673, 2481, 3723, 5600, 8415, 12630, 18863, 28395, 42620, 63907

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OFFSET

0,4

COMMENTS

See A222752 for the rows of numbers.

LINKS

Table of n, a(n) for n=0..31.

MATHEMATICA

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; nn = 15; t = Table[0, {nn}]; Do[c = Collatz[n]; e = Select[c, EvenQ]; diff = 2*Length[e] - Length[c]; If[diff < nn - 1, t[[diff + 2]]++], {n, 1, 2^(nn - 1), 2}]; t

CROSSREFS

Cf. A222752, A222754, A222755.

Sequence in context: A308107 A323167 A361651 * A274568 A233399 A226432

Adjacent sequences: A222750 A222751 A222752 * A222754 A222755 A222756

KEYWORD

nonn

AUTHOR

T. D. Noe, Mar 04 2013

STATUS

approved