OFFSET
1,3
LINKS
Toufik Mansour and Mark Shattuck, Counting set partitions by the number of movable letters, Journal of Difference Equations and Applications, 26:3, 384-403, (2020). On ResearchGate. See Theorem 8.
FORMULA
a(n) = (2*n - 1)*B(n)/2 - B(n+1)/2 + B(n-1)/2, where B(n) = A000110(n).
MATHEMATICA
a[n_]:=(2n-1)BellB[n]/2-BellB[n+1]/2+BellB[n-1]/2; Array[a, 24]
CROSSREFS
KEYWORD
nonn
AUTHOR
Stefano Spezia, Nov 19 2023
STATUS
approved