A377801 - OEIS

%I #24 Nov 13 2024 08:30:33

%S 1,1,1,2,1,5,1,3,5,15,1,2,4,13,26,52,1,7,29,203,1,877,1,2,3,4,5,6,9,

%T 10,12,15,18,20,23,30,36,45,46,60,69,90,92,115,138,180,207,230,276,

%U 345,414,460,690,828,1035,1380,2070,4140,1,3,7,19,21,53,57,133,159,371,399,1007,1113,3021,7049,21147

%N Irregular triangle read by rows: row n lists divisors of n-th Bell number.

%H Amiram Eldar, <a href="/A377801/b377801.txt">Table of n, a(n) for n = 0..7035</a> (rows 0..103 flattened)

%F T(n,k) = A027750(A000110(n),k).

%F T(n,2) = A279623(n) for n>=2.

%e Triangle begins:

%e   1,

%e   1,

%e   1,   2,

%e   1,   5,

%e   1,   3,  5,  15,

%e   1,   2,  4,  13, 26, 52,

%e   1,   7, 29, 203,

%e   1, 877,

%e   ...

%t Flatten[Table[Divisors[BellB[n]], {n, 0, 20}]]

%o (Magma) /* As triangle */ [Divisors(Bell(n)): n in [0..30]];

%Y Cf. A000110, A027750, A279623.

%Y Row sums give A262349.

%Y Row lengths give A278973.

%K nonn,tabf

%O 0,4

%A _Vincenzo Librandi_, Nov 07 2024