A272082 Irregular triangle read by rows: strictly decreasing positive integer sequences in lexicographic order with the property that the sum of inverses is an integer.

1, 6, 3, 2, 6, 3, 2, 1, 12, 6, 4, 2, 12, 6, 4, 2, 1, 15, 10, 3, 2, 15, 10, 3, 2, 1, 15, 12, 10, 4, 2, 15, 12, 10, 4, 2, 1, 15, 12, 10, 6, 4, 3, 15, 12, 10, 6, 4, 3, 1, 18, 9, 3, 2, 18, 9, 3, 2, 1, 18, 12, 9, 4, 2, 18, 12, 9, 4, 2, 1, 18, 12, 9, 6, 4, 3, 18, 12

Offset

1,2

Links

Peter Kagey, Table of n, a(n) for n = 1..4039 (All rows with first term less than or equal to 30.)

Example

First 8 rows:
[1]                because 1/1 is an integer
[6, 3, 2]          because 1/6 + 1/3 + 1/2 = 1.
[6, 3, 2, 1]       because 1/6 + 1/3 + 1/2 + 1/1 = 2.
[12, 6, 4, 2]      because 1/12 + 1/6 + 1/4 + 1/2 = 1.
[12, 6, 4, 2, 1]   because 1/12 + 1/6 + 1/4 + 1/2 + 1/1 = 2.
[15, 10, 3, 2]     because 1/15 + 1/10 + 1/3 + 1/2 = 1.
[15, 10, 3, 2, 1]  because 1/15 + 1/10 + 1/3 + 1/2 + 1/1 = 2.
[15, 12, 10, 4, 2] because 1/15 + 1/12 + 1/10 + 1/4 + 1/2 = 1.

Crossrefs

Cf. A272020, A272035, A272081, A272083.

Sequence in context: A348694 A049605 A088395 * A283443 A266263 A177707

Adjacent sequences: A272079 A272080 A272081 * A272083 A272084 A272085

Keyword

nonn,tabf

Author

Peter Kagey, Apr 19 2016

Status

approved