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A221531 Triangle read by rows: T(n,k) = A000005(n-k+1)*A000041(k-1), n>=1, k>=1. 0
1, 2, 1, 2, 2, 2, 3, 2, 4, 3, 2, 3, 4, 6, 5, 4, 2, 6, 6, 10, 7, 2, 4, 4, 9, 10, 14, 11, 4, 2, 8, 6, 15, 14, 22, 15, 3, 4, 4, 12, 10, 21, 22, 30, 22, 4, 3, 8, 6, 20, 14, 33, 30, 44, 30, 2, 4, 6, 12, 10, 28, 22, 45, 44, 60, 42, 6, 2, 8, 9, 20, 14, 44, 30, 66, 60, 84, 56 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

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

EXAMPLE

For n = 6:

-------------------------

k   A000041        T(6,k)

1      1  *  4   =    4

2      1  *  2   =    2

3      2  *  3   =    6

4      3  *  2   =    6

5      5  *  2   =   10

6      7  *  1   =    7

.         A000005

-------------------------

So row 6 is [4, 2, 6, 6, 10, 7]. Note that the sum of row 6 is 4+2+6+6+10+7 = 35 equals A006128(6).

.

Triangle begins:

1;

2,  1;

2,  2,  2;

3,  2,  4,  3;

2,  3,  4,  6, 5;

4,  2,  6,  6, 10, 7;

2,  4,  4,  9, 10, 14, 11;

4,  2,  8,  6, 15, 14, 22, 15;

3,  4,  4, 12, 10, 21, 22, 30, 22;

4,  3,  8,  6, 20, 14, 33, 30, 44, 30;

2,  4,  6, 12, 10, 28, 22, 45, 44, 60, 42;

6,  2,  8,  9, 20, 14, 44, 30, 66, 60, 84, 56;

...

CROSSREFS

Mirror of A221530. Columns 1-3: A000005, A000005, A062011. Leading diagonals 1-2: A000041, A139582. Row sums give A006128.

Cf. A140207, A182703.

Sequence in context: A261679 A147657 A029232 * A282970 A025807 A120254

Adjacent sequences:  A221528 A221529 A221530 * A221532 A221533 A221534

KEYWORD

nonn,tabl

AUTHOR

Omar E. Pol, Jan 19 2013

STATUS

approved

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Last modified April 5 22:49 EDT 2020. Contains 333260 sequences. (Running on oeis4.)