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A377801 Irregular triangle read by rows: row n lists divisors of n-th Bell number.

%I A377801 #24 Nov 13 2024 08:30:33
%S A377801 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 A377801 10,12,15,18,20,23,30,36,45,46,60,69,90,92,115,138,180,207,230,276,
%U A377801 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 A377801 Irregular triangle read by rows: row n lists divisors of n-th Bell number.
%H A377801 Amiram Eldar, <a href="/A377801/b377801.txt">Table of n, a(n) for n = 0..7035</a> (rows 0..103 flattened)
%F A377801 T(n,k) = A027750(A000110(n),k).
%F A377801 T(n,2) = A279623(n) for n>=2.
%e A377801 Triangle begins:
%e A377801   1,
%e A377801   1,
%e A377801   1,   2,
%e A377801   1,   5,
%e A377801   1,   3,  5,  15,
%e A377801   1,   2,  4,  13, 26, 52,
%e A377801   1,   7, 29, 203,
%e A377801   1, 877,
%e A377801   ...
%t A377801 Flatten[Table[Divisors[BellB[n]], {n, 0, 20}]]
%o A377801 (Magma) /* As triangle */ [Divisors(Bell(n)): n in [0..30]];
%Y A377801 Cf. A000110, A027750, A279623.
%Y A377801 Row sums give A262349.
%Y A377801 Row lengths give A278973.
%K A377801 nonn,tabf
%O A377801 0,4
%A A377801 _Vincenzo Librandi_, Nov 07 2024