A044949 Number of runs of odd length in the base-9 representation of n.

1, 1, 1, 1, 1, 1, 1, 1, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 1, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 1, 3, 3, 3, 3

Offset

1,9

Links

Antti Karttunen, Table of n, a(n) for n = 1..66430

Formula

As 731 = 1*(9^3) + 0*(9^2) + 0*(9^1) + 2*(9^0), it is written in base 9 (A007095) as "1002". There is one run of even length, and two runs of length 1 (thus of odd length), thus a(731) = 2. - Antti Karttunen, Dec 22 2017

Mathematica

Array[Count[Map[Length, Split@ IntegerDigits[#, 9]], _?OddQ] &, 105] (* Michael De Vlieger, Dec 22 2017 *)

Prog

(PARI) A044949(n) = { my(rl=0, d, prev_d = -1, s=0); while(n>0, d = (n%9); n = ((n-d)/9); if(d==prev_d, rl++, s += (rl%2); prev_d = d; rl = 1)); (s + (rl%2)); }; \\ Antti Karttunen, Dec 22 2017

Crossrefs

Cf. A007095, A043283, A043536, A044940, A044931.

Sequence in context: A044946 A044947 A044948 * A044950 A161872 A278248

Adjacent sequences: A044946 A044947 A044948 * A044950 A044951 A044952

Keyword

nonn,base

Author

Clark Kimberling

Extensions

More terms from Antti Karttunen, Dec 22 2017

Status

approved