cp's OEIS Frontend

A081289 a(0) = 0, a(n) = A081293(A081288(n)-1).

%I A081289 #6 Apr 28 2020 06:38:14
%S A081289 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 A081289 37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,37,107,107,107,
%U A081289 107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107,107
%N A081289 a(0) = 0, a(n) = A081293(A081288(n)-1).
%C A081289 After n>0, A081293(n) occurs A000245(n) times.
%o A081289 (PARI) A000108(n) = binomial(2*n, n)/(n+1);
%o A081289 A081293(n) = A000108(n) + sum(k=0, n, A000108(k));
%o A081289 A081288(n) = my(i=0); while(binomial(2*i, i)/(i+1) <= n, i++); i;
%o A081289 a(n) = if (n==0, 0, A081293(A081288(n)-1)); \\ _Michel Marcus_, Apr 28 2020
%Y A081289 Cf. A000108, A000245, A081288, A081290, A081293.
%K A081289 nonn
%O A081289 0,2
%A A081289 _Antti Karttunen_, Mar 17 2003