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Triangle read by rows: A130209 * A000012 * A127648.
1

%I #11 Jun 05 2023 21:20:15

%S 1,2,4,2,4,6,3,6,9,12,2,4,6,8,10,4,8,12,16,20,24,2,4,6,8,10,12,14,4,8,

%T 12,16,20,24,28,32,3,6,9,12,15,18,21,24,27,4,8,12,16,20,24,28,32,36,

%U 40,2,4,6,8,10,12,14,16,18,20,22,6,12,18,24,30,36,42,48,54,60,66,72

%N Triangle read by rows: A130209 * A000012 * A127648.

%C Row sums = A143272: (1, 6, 12, 30, 30, 84, 56, ...).

%C Left border = A000005: (1, 2, 2, 3, 2, 4, 2, 4, 3, ...).

%F T(n,k) = d(n)*k.

%e First few rows of the triangle =

%e 1;

%e 2, 4;

%e 2, 4, 6;

%e 3, 6, 9, 12;

%e 2, 4, 6, 8, 10;

%e 4, 8, 12, 16, 20, 24;

%e 2, 4, 6, 8, 10, 12, 14;

%e ...

%e T(5,3) = 6 = 2*3 = d(5)*3.

%o (PARI) tabl(nn) = for (n=1, nn, for (k=1, n, print1(numdiv(n)*k, ", "))); \\ _Michel Marcus_, Jun 05 2023

%Y Cf. A000005, A127648, A130209, A143272.

%K nonn,tabl

%O 1,2

%A _Gary W. Adamson_, Aug 03 2008

%E a(62) corrected by _Georg Fischer_, Jun 05 2023