OFFSET
0,2
COMMENTS
These are the chains counted in A293844 that are saturated. A chain C in poset P is saturated if there is no z in P - C such that x < z < y for some x,y in C and such that C union {z} is a chain.
FORMULA
a(n)/A005329(n) is the coefficient of x^n in eq(x)^2/(1 - x) where eq(x) is the q-exponential function.
a(n) ~ A299998 * 2^(n*(n+1)/2). - Vaclav Kotesovec, Apr 07 2020
MATHEMATICA
nn = 15; eq[z_] :=Sum[z^n/FunctionExpand[QFactorial[n, q]], {n, 0, nn}];
Table[FunctionExpand[QFactorial[n, q]] /. q -> 2, {n, 0, nn}] CoefficientList[Series[eq[z]^2/(1 - z) /. q -> 2, {z, 0, nn}], z]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Apr 05 2020
STATUS
approved