A086359 Fixed point if [decimal-digit-sum]-function at initial-value=A000984(n)=C[2n,n] is iterated.

2, 6, 2, 7, 9, 6, 3, 9, 2, 4, 3, 7, 2, 9, 9, 9, 9, 6, 3, 9, 3, 6, 9, 9, 9, 9, 2, 4, 3, 4, 5, 9, 3, 6, 9, 7, 5, 6, 2, 7, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 6, 3, 9, 3, 6, 9, 9, 9, 9, 3, 6, 9, 6, 3, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 2, 4, 3, 4, 5, 9, 3, 6, 9, 4, 8, 6, 5, 4, 9, 9, 9, 9, 3, 6, 9, 6, 3, 9, 9

Offset: 1

Author

Labos Elemer, Jul 21 2003

Keywords

• base
• nonn

Examples

			n=10, C[20,10]=184756, iteration list={184756,31,4},a(10)=4.
		

Crossrefs

Cf. A086353-A086361, A007953, A010888, A038194, A029898.

Programs

Mathematica

sud[x_] := Apply[Plus, DeleteCases[IntegerDigits[x], 0]] Table[FixedPoint[sud, Binomial[2*w, w]], {w, 1, 128}]

Formula

a(n)=A010888[C[2n, n]]=fixed-point of A007953[C[2n, n]]; It equals C[2n, n] modulo(9); at r=0 use 9.