A256113 Table read by rows: T(1,1) = 1, for n > 1: row n = union of distinct prime factors occurring in terms of n-th row of Pascal's triangle, cf. A007318.

1, 2, 3, 2, 3, 2, 5, 2, 3, 5, 3, 5, 7, 2, 5, 7, 2, 3, 7, 2, 3, 5, 7, 2, 3, 5, 7, 11, 2, 3, 5, 7, 11, 2, 3, 5, 11, 13, 2, 3, 7, 11, 13, 3, 5, 7, 11, 13, 2, 3, 5, 7, 11, 13, 2, 5, 7, 11, 13, 17, 2, 3, 5, 7, 11, 13, 17, 2, 3, 7, 11, 13, 17, 19, 2, 3, 5, 11, 13

Offset: 1

Author

Reinhard Zumkeller, Mar 16 2015

Keywords

• nonn
• tabf

Examples

			.  n |   T(n,k)   |                A001142(n) | A007318(n,0..n)
. ---+------------+---------------------------+-------------------------
.  1 | 1          |                         1 | 1  1
.  2 | 2          |                         2 | 1  2  1
.  3 | 3          |                         9 | 1  3  3   1
.  4 | 2 3        |                        96 | 1  4  6   4   1
.  5 | 2 5        |                      2500 | 1  5 10  10   5   1
.  6 | 2 3 5      |                    162000 | 1  6 15  20  15   6   1
.  7 | 3 5 7      |                  26471025 | 1  7 21  35  35  21   7   1
.  8 | 2 5 7      |               11014635520 | 1  8 28  56  70  56  28 ...
.  9 | 2 3 7      |            11759522374656 | 1  9 36  84 126 126  84 ...
. 10 | 2 3 5 7    |         32406091200000000 | 1 10 45 120 210 252 210 ...
. 11 | 2 3 5 7 11 |     231627686043080250000 | 1 11 55 165 330 462 462 ...
. 12 | 2 3 5 7 11 | 4311500661703860387840000 | 1 12 66 220 495 792 924 ...
		

Links

• Reinhard Zumkeller, b-file >>Rows n = 1..1000 of triangle, flattened
• Index entries for triangles and arrays related to Pascal's triangle

Crossrefs

Cf. A007318, A027748, A001142, A004788 (row lengths), A056606 (row products).

Programs

Haskell

a256113 n k = a256113_tabf !! (n-1) !! (n-1)
a256113_row n = a256113_tabf !! (n-1)
a256113_tabf = map a027748_row $ tail a001142_list