Stamp folding $s(9)$

The number of distinct ways to fold a strip of $9$ labeled stamps.

Updates

• Lower bound: $4536$
  Reference unknown
  [via Number of ways of folding a strip of n labeled stamps. - OEIS]
• Upper bound: $4536$
  Reference unknown
  [via Number of ways of folding a strip of n labeled stamps. - OEIS]