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A265157 Number of 2's in the base-3 representation of 2^n - 1. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,10
LINKS
FORMULA
a(n) = A081603(A000225(n)). - Michel Marcus, Dec 03 2015
a(n) = A260683(n) - A000035(n). - Robert Israel, Dec 03 2015
MATHEMATICA
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 *)
PROG
(PARI) a(n) = {my(d = digits(n, 3)); sum(k=1, #d, d[k]==2); } \\ Michel Marcus, Dec 03 2015
CROSSREFS
Cf. A000079 (2^n), A000225 (2*n - 1).
Cf. A260683 (Number of 2's in the expansion of 2^n in base 3).
Sequence in context: A324030 A275821 A291674 * A054263 A308656 A178775
KEYWORD
nonn,base
AUTHOR
L. Edson Jeffery, Dec 02 2015
STATUS
approved

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)