A278447 Irregular triangle read by rows in which row n lists the semiperimeters of the parts of the symmetric representation of sigma(n).

2, 4, 3, 3, 8, 4, 4, 12, 5, 5, 16, 6, 4, 6, 10, 10, 7, 7, 24, 8, 8, 13, 13, 9, 8, 9, 32

Offset

1,1

Links

Table of n, a(n) for n=1..27.

Formula

a(n) = A279160(n)/2.

Example

Triangle begins:
2;
4;
3, 3;
8;
4, 4;
12;
5, 5;
16;
6, 4, 6;
10, 10;
7, 7;
24;
8, 8;
13, 13;
9, 8, 9;
32;
...
For n = 9 the symmetric representation of sigma(9) = 13 has three parts of areas 5, 3, 5 respectively. The perímeters of the parts are 12, 8 and 12, so the 9th row of triangle lists the semiperimeters: 6, 4, 6.

Crossrefs

Row sums give A244363.

Cf. A237271 gives the row lengths.

Cf. A000203, A196020, A236104, A235791, A237270, A237591, A237593, A245092, A262626, A279160.

Sequence in context: A303354 A330256 A227418 * A235590 A069655 A353706

Adjacent sequences: A278444 A278445 A278446 * A278448 A278449 A278450

Keyword

nonn,tabf,more

Author

Omar E. Pol, Dec 07 2016

Status

approved