A129574 - OEIS

%I #7 Aug 10 2018 16:22:45

%S 1,2,3,3,3,4,4,3,4,5,4,4,4,4,6,5,3,5,5,4,6,6,4,4,5,5,6,6,4,6,6,3,5,6,

%T 6,7,5,4,6,6,4,6,6,4,8,8,4,4,5,6,7,6,4,6,8,6,6,6,4,6,6,4,8,7,5,8,6,4,

%U 6,8,6,5,5,4,8,8,6,8,6,4,7,7,4,6,8,6,6,6,4,8

%N Number of odd divisors of n plus the number of odd divisors of n - 1.

%H Andrew Howroyd, <a href="/A129574/b129574.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A001227(n) + A001227(n-1). - _Andrew Howroyd_, Aug 10 2018

%e a(4) = 3 = sum of row 4 of triangle A129573: (1 + 0 + 1 + 1).

%o (PARI) a(n)=numdiv(n >> valuation(n,2)) + if(n > 1, numdiv((n-1) >> valuation(n-1,2))) \\ _Andrew Howroyd_, Aug 10 2018

%Y Row sums of A129573.

%Y Cf. A001227.

%K nonn

%O 1,2

%A _Gary W. Adamson_, Apr 22 2007

%E Name changed and terms a(11) and beyond from _Andrew Howroyd_, Aug 10 2018