A348649 - OEIS

%I #12 Oct 28 2021 12:03:30

%S 1,1,1,1,3,1,1,7,1,1,15,25,1,1,31,65,15,1,1,63,301,21,1,1,127,1701,1,

%T 1,255,3025,6951,1,1,511,34105,42525,22827,45,1,1,1023,28501,179487,

%U 63987,1155,55,1,1,2047,611501,159027,22275,1705,1,1,4095,261625,7508501,39325,2431,1

%N Odd numbers in the triangle of Stirling numbers of the second kind (A008277).

%C We take the odd values in A008277, as they appear, with duplicates.

%C For any n >= 1, the n-th row has A007306(n) terms.

%H Rémy Sigrist, <a href="/A348649/b348649.txt">Table of n, a(n) for n = 1..10057</a> (rows for n = 1..331, flattened)

%H Rémy Sigrist, <a href="/A348649/a348649.png">Logarithmic scatterplot of the first 35000 terms</a>

%H <a href="/index/St#Stirling">Index entries for sequences related to Stirling numbers</a>

%e As an irregular table, the first rows are:

%e      1:    1;

%e      2:    1, 1;

%e      3:    1, 3, 1;

%e      4:    1, 7, 1;

%e      5:    1, 15, 25, 1;

%e      6:    1, 31, 65, 15, 1;

%e      7:    1, 63, 301, 21, 1;

%e      8:    1, 127, 1701, 1;

%e      9:    1, 255, 3025, 6951, 1;

%e     10:    1, 511, 34105, 42525, 22827, 45, 1;

%e     11:    1, 1023, 28501, 179487, 63987, 1155, 55, 1;

%e     ...

%o (PARI) row(n) = select(v -> v%2==1, vector(n, k, stirling(n, k, 2)))

%Y See A014421, A014428, A014450, A014459 for similar sequences.

%Y Cf. A007306, A008277, A348650 (even numbers).

%K nonn,tabf

%O 1,5

%A _Rémy Sigrist_, Oct 27 2021