A260683 -id:A260683 - cp's OEIS frontend

A036461 Number of 1 digits in base 3 representation of 2^n.

1, 0, 2, 0, 2, 2, 2, 2, 4, 0, 4, 2, 4, 2, 6, 4, 2, 4, 6, 2, 6, 4, 6, 4, 8, 2, 10, 4, 4, 8, 6, 8, 8, 8, 8, 6, 10, 8, 10, 10, 6, 6, 12, 8, 10, 14, 8, 10, 10, 12, 16, 8, 12, 18, 10, 10, 14, 10, 14, 14, 16, 10, 16, 12, 16, 16, 14, 16, 14, 18, 20, 12, 20, 10, 22, 12, 26, 8, 20, 12, 22, 14, 16

Offset: 0

David W. Wilson

The number of 1's in the base 3 representation of any even(odd) number is even(odd).

Robert Israel, Table of n, a(n) for n = 0..10000

Cf. A020915 (number of digits), A104320 (number of 0's), A260683 (number of 2's).

seq(numboccur(1,convert(2^n,base,3)),n=0..100); # Robert Israel, Apr 04 2018

Table[DigitCount[2^n,3,1],{n,0,120}]  (* Harvey P. Dale, Mar 14 2011 *)

a(n) = #select(x->(x==1), digits(2^n, 3)); \\ Michel Marcus, Apr 04 2018

A265157 Number of 2's in the base-3 representation of 2^n - 1.

Original entry on oeis.org

0, 0, 0, 1, 1, 0, 1, 1, 0, 3, 2, 3, 3, 2, 2, 5, 5, 4, 3, 6, 4, 6, 5, 3, 1, 4, 2, 7, 8, 6, 9, 8, 8, 6, 7, 7, 4, 5, 8, 8, 11, 10, 7, 10, 10, 7, 9, 7, 8, 9, 11, 15, 13, 9, 9, 11, 13, 15, 12, 12, 15, 14, 11, 14, 16, 13, 14, 11, 14, 14, 14, 15

Offset: 0

L. Edson Jeffery, Dec 02 2015

Indranil Ghosh, Table of n, a(n) for n = 0..1000

Cf. A000079 (2^n), A000225 (2*n - 1).
Cf. A260683 (Number of 2's in the expansion of 2^n in base 3).
Cf. A000035, A081603.

n = -1; While[n < 71, n++; s = IntegerDigits[2^n - 1, 3]; k = Count[s, 2]; AppendTo[a, k]]; a (* after Emmanuel Vantieghem (see A260683)*)
Table[DigitCount[2^n-1,3,2],{n,0,80}] (* Harvey P. Dale, Dec 04 2015 *)

a(n) = {my(d = digits(n, 3)); sum(k=1, #d, d[k]==2);} \\ Michel Marcus, Dec 03 2015

a(n) = A081603(A000225(n)). - Michel Marcus, Dec 03 2015

a(n) = A260683(n) - A000035(n). - Robert Israel, Dec 03 2015

cp's OEIS Frontend

A036461 Number of 1 digits in base 3 representation of 2^n.

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