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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). 3
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 (list; table; graph; refs; listen; history; text; internal format)
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: A290308 A159005 A144859 * A010172 A224365 A087869

Adjacent sequences:  A280516 A280517 A280518 * A280520 A280521 A280522

KEYWORD

nonn,tabl

AUTHOR

Max Alekseyev, Jan 04 2017

STATUS

approved

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Last modified April 25 12:04 EDT 2019. Contains 322456 sequences. (Running on oeis4.)