A046818 - OEIS

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

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OFFSET

0,3

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.

FORMULA

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

a(n) = A240883(n) + 1. - 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 *)