A339674 - OEIS

%I #23 Feb 24 2021 08:20:22

%S 0,0,1,0,1,2,3,0,3,0,3,4,7,0,1,2,3,4,5,6,7,0,1,6,7,0,7,0,7,8,15,0,1,6,

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

%U 0,3,12,15,0,1,2,3,12,13,14,15,0,1,14,15,0

%N Irregular triangle T(n, k), n, k >= 0, read by rows; for any number m with runs in binary expansion (r_1, ..., r_j), let R(m) = {r_1 + ... + r_j, r_2 + ... + r_j, ..., r_j}; row n corresponds to the numbers k such that R(k) is included in R(n), in ascending order.

%C For any m > 0, R(m) contains the partial sums of the m-th row of A227736; by convention, R(0) = {}.

%C The underlying idea is to take some or all of the rightmost runs of a number, and possibly merge some of them.

%C For any n >= 0, the n-th row:

%C - has 2^A000120(A003188(n)) terms,

%C - has first term 0 and last term A003817(n),

%C - has n at position A090079(n),

%C - corresponds to the distinct terms in n-th row of table A341840.

%H Rémy Sigrist, <a href="/A339674/b339674.txt">Table of n, a(n) for n = 0..6560</a>

%H Rémy Sigrist, <a href="/A339674/a339674.png">Scatterplot of (n, T(n, k)) for n <= 2^10</a>

%H Rémy Sigrist, <a href="/A339674/a339674.gp.txt">PARI program for A339674</a>

%H <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>

%F T(n, 0) = 0.

%F T(n, A090079(n)) = n.

%F T(n, 2^A000120(A003188(n))-1) = A003817(n).

%e The triangle starts:

%e     0;

%e     0, 1;

%e     0, 1, 2, 3;

%e     0, 3;

%e     0, 3, 4, 7;

%e     0, 1, 2, 3, 4, 5, 6, 7;

%e     0, 1, 6, 7;

%e     0, 7;

%e     0, 7, 8, 15;

%e     0, 1, 6, 7, 8, 9, 14, 15;

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

%e     0, 3, 4, 7, 8, 11, 12, 15;

%e     0, 3, 12, 15;

%e     0, 1, 2, 3, 12, 13, 14, 15;

%e     0, 1, 14, 15;

%e     0, 15;

%e     ...

%o (PARI) See Links section.

%Y Cf. A000120, A003188, A003817, A090079, A227736, A341840.

%K nonn,base,tabf

%O 0,6

%A _Rémy Sigrist_, Feb 21 2021