A240750 Table where row n contains all compositions of n into an even number of parts.

1, 1, 2, 1, 1, 2, 3, 1, 2, 2, 1, 3, 1, 1, 1, 1, 4, 1, 3, 2, 2, 3, 2, 1, 1, 1, 1, 4, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 5, 1, 4, 2, 3, 3, 3, 1, 1, 1, 2, 4, 2, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 5, 1, 3, 1, 1, 1, 2, 2, 1, 1, 2, 1, 2, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1

Offset

2,3

Comments

Can also be regarded as a table where row n is the n-th composition into an even number of parts, sorted by sum of composition and then reverse lexicographically.

Links

Table of n, a(n) for n=2..97.

Example

The table starts:
{}
(none)
11
21,12
31,22,13,1111
41,32,23,2111,14,1211,1121,1112
51,42,33,3111,24,2211,2121,2112,15,1311,1221,1212,1131,1122,1113,111111

Prog

(PARI) evil(n) = local(r=0, m=n); while(m>0, if(m%2==1, r=1-r); m\=2); n*2+r
A066099row(n) = {local(v=vector(n), j=0, k=0);
   while(n>0, k++; if(n%2==1, v[j++]=k; k=0); n\=2);
   vector(j, i, v[j-i+1])}
arow(n)=A066099row(evil(n))

Crossrefs

Cf. A066099, A240837, A001969, A034008 (compositions in rows), A087447 (parts in rows for n>2).

Sequence in context: A105810 A063726 A290267 * A181118 A179009 A112757

Adjacent sequences: A240747 A240748 A240749 * A240751 A240752 A240753

Keyword

nonn,tabf

Author

Franklin T. Adams-Watters, Apr 12 2014

Status

approved