A230585 First terms of first rows of zigzag matrices as defined in A088961.

3, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440, 9694845, 35357670, 129644790, 477638700, 1767263190, 6564120420, 24466267020, 91482563640, 343059613650, 1289904147324, 4861946401452, 18367353072152, 69533550916004, 263747951750360

Offset: 1

Author

Reinhard Zumkeller, Oct 25 2013

Keywords

• nonn

Comments

a(n) = A088961(A056520(n-1));

a(n) = A000108(n+1) for n > 1.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A007318.

Programs

Haskell

a230585 1 = 3
a230585 n = a007318 (2*n) n - a007318 (2*n) (n+2)

Formula

a(n) = binomial(2*n,n) - binomial(2*n,n+2) + 0^(n-1).