A240750 - OEIS

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

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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)

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