cp's OEIS Frontend

A268688 a(n) = (A266203(n)-1)/2 if n>0, and a(0) = 0.

%I A268688 #19 Jan 11 2020 15:57:47
%S A268688 0,0,1,2,10,30,190,1022
%N A268688 a(n) = (A266203(n)-1)/2 if n>0, and a(0) = 0.
%C A268688 The maximum values of k where g_k(n) is the maximal value.
%C A268688 g_k(n) is the weak Goodstein function defined in A266202.
%C A268688 Next term: 3*2^402653210-1.
%e A268688 g_1(4) = b_2(4)-1 = b_2(2^2)-1 = 3^2-1 = 8;
%e A268688 g_2(4) = b_3(2*3+2)-1 = 2*4 + 2-1 = 9;
%e A268688 g_3(4) = b_4(2*4 + 1 ) -1 = 2*5 + 1-1 = 10;
%e A268688 g_4(4) = b_5(2*5) -1= 2*6 - 1 = 11;
%e A268688 g_5(4) = b_6(6+5)-1 = 7+5-1 = 11;
%e A268688 g_6(4) = b_7(7+4)-1 = 8+4-1 = 11;
%e A268688 g_7(4) = b_8(8+3)-1 = 9+3-1 = 11;
%e A268688 g_8(4) = b_9(9+2)-1 = 10+2-1 = 11;
%e A268688 g_9(4) = b_10(10+1)-1 = 11+1-1 = 11;
%e A268688 g_10(4) = b_11(11)-1 = 12-1 = 11;
%e A268688 g_11(4) = b_12(11)-1 = 11-1 = 10;
%e A268688 g_12(4) = b_13(10)-1 = 10-1 = 9;
%e A268688 g_13(4) = b_14(9)-1 = 9-1 = 8;
%e A268688 …
%e A268688 g_21(4) = 0;
%e A268688 So a(4) = 10.
%Y A268688 Cf. A266203, A268687, A268689.
%K A268688 nonn
%O A268688 0,4
%A A268688 _Natan Arie Consigli_, Apr 02 2016