cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A339106 Triangle read by rows: T(n,k) = A000203(n-k+1)*A000041(k-1), n >= 1, 1 <= k <= n.

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%I A339106 #48 Jan 10 2021 11:21:36
%S A339106 1,3,1,4,3,2,7,4,6,3,6,7,8,9,5,12,6,14,12,15,7,8,12,12,21,20,21,11,15,
%T A339106 8,24,18,35,28,33,15,13,15,16,36,30,49,44,45,22,18,13,30,24,60,42,77,
%U A339106 60,66,30,12,18,26,45,40,84,66,105,88,90,42,28,12,36,39,75,56,132,90,154,120,126,56
%N A339106 Triangle read by rows: T(n,k) = A000203(n-k+1)*A000041(k-1), n >= 1, 1 <= k <= n.
%C A339106 Conjecture 1: T(n,k) is the sum of all divisors of all (n - k + 1)'s in the n-th row of triangle A176206, assuming that A176206 has offset 1. The same for the triangle A340061.
%C A339106 Conjecture 2: the sum of row n equals A066186(n), the sum of all parts of all partitions of n.
%F A339106 T(n,k) = sigma(n-k+1)*p(k-1), n >= 1, 1 <= k <= n.
%e A339106 Triangle begins:
%e A339106    1;
%e A339106    3,  1;
%e A339106    4,  3,  2;
%e A339106    7,  4,  6,  3;
%e A339106    6,  7,  8,  9,  5;
%e A339106   12,  6, 14, 12, 15,  7;
%e A339106    8, 12, 12, 21, 20, 21,  11;
%e A339106   15,  8, 24, 18, 35, 28,  33,  15;
%e A339106   13, 15, 16, 36, 30, 49,  44,  45,  22;
%e A339106   18, 13, 30, 24, 60, 42,  77,  60,  66,  30;
%e A339106   12, 18, 26, 45, 40, 84,  66, 105,  88,  90,  42;
%e A339106   28, 12, 36, 39, 75, 56, 132,  90, 154, 120, 126, 56;
%e A339106 ...
%e A339106 For n = 6 the calculation of every term of row 6 is as follows:
%e A339106 -------------------------
%e A339106 k   A000041        T(6,k)
%e A339106 1      1  *  12  =   12
%e A339106 2      1  *  6   =    6
%e A339106 3      2  *  7   =   14
%e A339106 4      3  *  4   =   12
%e A339106 5      5  *  3   =   15
%e A339106 6      7  *  1   =    7
%e A339106 .         A000203
%e A339106 -------------------------
%e A339106 The sum of row 6 is 12 + 6 + 14 + 12 + 15 + 7 = 66, equaling A066186(6).
%t A339106 T[n_, k_] := DivisorSigma[1, n - k + 1] * PartitionsP[k - 1]; Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* _Amiram Eldar_, Jan 08 2021 *)
%o A339106 (PARI) T(n, k) = sigma(n-k+1)*numbpart(k-1); \\ _Michel Marcus_, Jan 08 2021
%Y A339106 Mirror of A221529.
%Y A339106 Row sums give A066186 (conjectured).
%Y A339106 Main diagonal gives A000041.
%Y A339106 Columns 1 and 2 give A000203.
%Y A339106 Column 3 gives A074400.
%Y A339106 Column 4 gives A272027.
%Y A339106 Column 5 gives A274535.
%Y A339106 Column 6 gives A319527.
%Y A339106 Cf. A176206, A340061.
%K A339106 nonn,tabl
%O A339106 1,2
%A A339106 _Omar E. Pol_, Nov 23 2020