A248836 Number of length n arrays x(i), i=1..n with x(i) in 0..i and no value appearing more than 2 times

2, 6, 22, 96, 482, 2736, 17302, 120576, 917762, 7574016, 67354582, 642041856, 6530291042, 70589700096, 808090395862, 9766250151936, 124258689304322, 1660195646078976, 23239748527125142, 340125128186658816

Offset

1,1

Comments

Column 2 of A248842

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Example

Some solutions for n=6
..1....1....1....1....1....0....1....0....0....0....1....0....1....1....1....0
..0....2....2....0....2....2....2....2....2....1....1....1....2....0....0....1
..0....3....0....1....2....1....2....1....1....1....0....3....0....1....2....0
..1....4....0....0....4....2....0....3....3....2....3....3....4....0....0....2
..4....0....3....4....3....4....4....0....1....5....4....2....2....2....2....4
..5....6....4....5....4....0....3....6....6....5....0....2....5....4....4....4

Crossrefs

Sequence in context: A006871 A268699 A253948 * A351919 A328500 A180389

Adjacent sequences: A248833 A248834 A248835 * A248837 A248838 A248839

Keyword

nonn

Author

R. H. Hardin, Oct 15 2014

Status

approved