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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A181290 The sum of the lengths of the 2-compositions of n. A 2-composition of n is a nonnegative matrix with two rows, such that each column has at least one nonzero entry and whose entries sum up to n. The length of the 2-composition is the number of columns.

Table of values

n a(n)
0 0
1 2
2 11
3 52
4 227
5 944
6 3800
7 14944
8 57748
9 220128
10 829968
11 3101376
12 11502704
13 42393088
14 155392768
15 566918144
16 2059768384
17 7456496128
18 26905720576
19 96804463616
20 347386161920
21 1243665567744
22 4442849839104
23 15840448094208
24 56375692407808
25 200307512532992
26 710622022258688
27 2517475213557760

List of values

[0, 2, 11, 52, 227, 944, 3800, 14944, 57748, 220128, 829968, 3101376, 11502704, 42393088, 155392768, 566918144, 2059768384, 7456496128, 26905720576, 96804463616, 347386161920, 1243665567744, 4442849839104, 15840448094208, 56375692407808, 200307512532992, 710622022258688, 2517475213557760]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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