A129265 - OEIS

%I #20 Jan 27 2021 09:47:00

%S 1,2,1,1,1,1,3,2,1,1,1,1,1,1,1,2,2,2,1,1,1,1,1,1,1,1,1,1,4,3,2,2,1,1,

%T 1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,3,

%U 3,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1

%N Triangle read by rows: T(n,k) is the number of power of two divisors of n that are less than or equal to n/k.

%C Equals A115361 * A000012 as infinite lower triangular matrices (cf. A129264).

%H Andrew Howroyd, <a href="/A129265/b129265.txt">Table of n, a(n) for n = 1..1275</a>

%F T(n,k) = 1 for n odd.

%e First few rows of the triangle are:

%e   1;

%e   2, 1;

%e   1, 1, 1;

%e   3, 2, 1, 1;

%e   1, 1, 1, 1, 1;

%e   2, 2, 2, 1, 1, 1;

%e   1, 1, 1, 1, 1, 1, 1;

%e   ...

%o (PARI) T(n, k)={sumdiv(n, d, d <= n/k && d==1<<valuation(d, 2))} \\ _Andrew Howroyd_, Aug 07 2018

%Y Row sums are A129527.

%Y Column 1 is A001511.

%Y Cf. A115361, A000012, A129264.

%K nonn,tabl

%O 1,2

%A _Gary W. Adamson_, Apr 06 2007

%E Name changed and terms a(56) and beyond from _Andrew Howroyd_, Aug 07 2018