A081289 - OEIS

%I #6 Apr 28 2020 06:38:14

%S 0,3,6,6,6,14,14,14,14,14,14,14,14,14,37,37,37,37,37,37,37,37,37,37,

%T 37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,107,107,107,

%U 107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107

%N a(0) = 0, a(n) = A081293(A081288(n)-1).

%C After n>0, A081293(n) occurs A000245(n) times.

%o (PARI) A000108(n) = binomial(2*n, n)/(n+1);

%o A081293(n) = A000108(n) + sum(k=0, n, A000108(k));

%o A081288(n) = my(i=0); while(binomial(2*i, i)/(i+1) <= n, i++); i;

%o a(n) = if (n==0, 0, A081293(A081288(n)-1)); \\ _Michel Marcus_, Apr 28 2020

%Y Cf. A000108, A000245, A081288, A081290, A081293.

%K nonn

%O 0,2

%A _Antti Karttunen_, Mar 17 2003