A216640 Number of nondecreasing arrays of n 1..n integers with the sum of their 2nd powers equal to sum(i^2,i=1..n)

1, 1, 1, 1, 1, 3, 8, 25, 83, 257, 788, 2491, 7885, 25099, 80481, 264505, 884517, 2994535, 10208806, 35095825, 121699761, 424273761, 1487693075, 5244197347, 18584820912, 66169376686, 236592018517, 849466213882, 3061492852986, 11072927827447

Offset

1,6

Comments

Column 2 of A216645

Links

R. H. Hardin, Table of n, a(n) for n = 1..49

Example

All solutions for n=6
..1....3....1
..2....3....1
..3....4....1
..4....4....4
..5....4....6
..6....5....6

Crossrefs

Sequence in context: A161634 A293385 A258466 * A148794 A143330 A148795

Adjacent sequences: A216637 A216638 A216639 * A216641 A216642 A216643

Keyword

nonn

Author

R. H. Hardin Sep 11 2012

Status

approved