A280519 Triangle read by rows: T(n,k) = number of sequences of n positive integers with reciprocals adding up to k (k=1,2,...,n).

1, 1, 1, 10, 3, 1, 215, 41, 6, 1, 12231, 1115, 105, 10, 1, 2025462, 74862, 3466, 215, 15, 1, 1351857641, 14294210, 267281, 8372, 385, 21, 1, 6255560531733, 10837663111, 57646358, 727049, 17318, 630, 28, 1

Offset

1,4

Links

Table of n, a(n) for n=1..36.

Example

Triangle starts with:
n=1: 1
n=2: 1, 1
n=3: 10, 3, 1
n=4: 215, 41, 6, 1
n=5: 12231, 1115, 105, 10, 1
n=6: 2025462, 74862, 3466, 215, 15, 1
...

Crossrefs

Cf. A280517 (row sums), A002967 (column k=1), A156869 (nondecreasing sequences), A280520 (increasing sequences).

Sequence in context: A352689 A159005 A144859 * A010172 A224365 A087869

Adjacent sequences: A280516 A280517 A280518 * A280520 A280521 A280522

Keyword

nonn,tabl

Author

Max Alekseyev, Jan 04 2017

Status

approved