2652244

Appears in sequences

• Related to Euler numbers, expansion of e.g.f. sec(x)*tan^2(x).at n=8A002735
• Number of down-up permutations of n+3 starting with n+1.at n=10A006212
• a(n) = n! * [x^n] 2*(tan(x))^2*(sec(x) + tan(x)).at n=10A164575