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

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, 8, 24, 18, 35, 28, 33, 15, 13, 15, 16, 36, 30, 49, 44, 45, 22, 18, 13, 30, 24, 60, 42, 77, 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

Offset

1,2

Comments

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.

Conjecture 2: the sum of row n equals A066186(n), the sum of all parts of all partitions of n.

Links

Table of n, a(n) for n=1..78.

Formula

T(n,k) = sigma(n-k+1)*p(k-1), n >= 1, 1 <= k <= n.

Example

Triangle begins:
   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,  8, 24, 18, 35, 28,  33,  15;
  13, 15, 16, 36, 30, 49,  44,  45,  22;
  18, 13, 30, 24, 60, 42,  77,  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;
...
For n = 6 the calculation of every term of row 6 is as follows:
-------------------------
k   A000041        T(6,k)
1      1  *  12  =   12
2      1  *  6   =    6
3      2  *  7   =   14
4      3  *  4   =   12
5      5  *  3   =   15
6      7  *  1   =    7
.         A000203
-------------------------
The sum of row 6 is 12 + 6 + 14 + 12 + 15 + 7 = 66, equaling A066186(6).

Mathematica

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 *)

Prog

(PARI) T(n, k) = sigma(n-k+1)*numbpart(k-1); \\ Michel Marcus, Jan 08 2021

Crossrefs

Mirror of A221529.

Row sums give A066186 (conjectured).

Main diagonal gives A000041.

Columns 1 and 2 give A000203.

Column 3 gives A074400.

Column 4 gives A272027.

Column 5 gives A274535.

Column 6 gives A319527.

Cf. A176206, A340061.

Sequence in context: A152842 A307280 A209704 * A082909 A335906 A029151

Adjacent sequences: A339103 A339104 A339105 * A339107 A339108 A339109

Keyword

nonn,tabl

Author

Omar E. Pol, Nov 23 2020

Status

approved