A046818 Number of 1's in binary expansion of 3n+1.

1, 1, 3, 2, 3, 1, 3, 3, 3, 3, 5, 2, 3, 2, 4, 4, 3, 3, 5, 4, 5, 1, 3, 3, 3, 3, 5, 3, 4, 3, 5, 5, 3, 3, 5, 4, 5, 3, 5, 5, 5, 5, 7, 2, 3, 2, 4, 4, 3, 3, 5, 4, 5, 2, 4, 4, 4, 4, 6, 4, 5, 4, 6, 6, 3, 3, 5, 4, 5, 3, 5, 5, 5, 5, 7, 4, 5, 4, 6, 6, 5, 5, 7, 6, 7, 1, 3, 3, 3, 3, 5, 3, 4

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• base

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
• S. R. Finch, P. Sebah and Z.-Q. Bai, Odd Entries in Pascal's Trinomial Triangle, arXiv:0802.2654 [math.NT], 2008.

Crossrefs

Cf. A000120, A016777 (3n+1).

Programs

Haskell

a046818 = a000120 . a016777  -- Reinhard Zumkeller, Apr 14 2014

Mathematica

Table[Count[IntegerDigits[3 n + 1, 2], 1], {n, 0, 92}] (* Jayanta Basu, Jun 29 2013 *)
DigitCount[#,2,1]&/@(3Range[0,100]+1) (* Harvey P. Dale, Apr 03 2021 *)

Formula

a(n) = A000120(3n+1).

a(n) = A240883(n) + 1. - Reinhard Zumkeller, Apr 14 2014