A138176 Hankel transform of A138175.

1, -4, 144, -43264, 106832896, -2155963622400, 354617391605760000, -474686810341051524710400, 5166329306435680284163452174336, -456900249341808231214942590547243565056

Offset

0,2

Comments

When aerated, gives Hankel transform of A138175. sqrt(abs(a(n))/2^n=A005156(n).

Links

Table of n, a(n) for n=0..9.

A. V. Razumov and Yu. G. Stroganov, On refined enumerations of some symmetry classes of alternating sign matrices

Formula

a(n)=(-1)^n*product{k=1..n, (6k-2)!(2k-1)!/((4k-1)!(4k-2)!)}^2

Crossrefs

Sequence in context: A069135 A186081 A375416 * A203424 A055209 A239350

Adjacent sequences: A138173 A138174 A138175 * A138177 A138178 A138179

Keyword

easy,sign

Author

Paul Barry, Mar 03 2008

Status

approved