A180072 Number of permutations of 1..n with the sum of squared adjacent differences <= (n-1)*n*(n+1)/6.

2, 2, 12, 62, 384, 2574, 20432, 183790, 1833102, 20075568, 240972780, 3128714960, 43794182164, 656192916356, 10493589363960, 178319646743428

Offset

2,1

Links

Table of n, a(n) for n=2..17.

Crossrefs

Cf. A000292, A180073.

Sequence in context: A352526 A131444 A291541 * A367546 A013315 A032321

Adjacent sequences: A180069 A180070 A180071 * A180073 A180074 A180075

Keyword

nonn,more

Author

R. H. Hardin, Aug 09 2010

Extensions

a(14) from Donovan Johnson, Oct 11 2010

a(15)-a(17) from Martin Ehrenstein, Nov 16 2023

Status

approved