119992domain: NAppears in sequencesPentagonal numbers (A000326) whose digit reversal is a brilliant number (A078972).at n=16A115680Binomial variation of the Catalan numbers: a(n) = sum( binomial(n-i, i)*a(i)*a(n-1-i), i=0..(n-1) ) with a(0)=1.at n=10A188479