This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075876 #20 Mar 12 2025 04:44:49 %S A075876 0,2,4,12,52,212,852,3412,13652,54612,218452,873812,3495252,13981012, %T A075876 55924052,223696212 %N A075876 Values of m for which A075825(m) = 1. %C A075876 For n > 4 it appears that a(n) = 4*a(n-1) + 4. %C A075876 From _Robert Israel_, Nov 08 2016: (Start) %C A075876 By induction, we have for k >= 0: %C A075876 A075825((10*4^k-7)/3) = 2^(k+1) %C A075876 A075825((10*4^k-4)/3) = 1 %C A075876 A075825((10*4^k-1)/3) = 2^(k+1)+1 %C A075876 A075825((20*4^k-8)/3) = 2^(k+1)-1 %C A075876 A075825((20*4^k-5)/3) = 2^(k+1)+1 %C A075876 A075825((20*4^k-1)/3) = 2^(k+1) %C A075876 In particular, this sequence contains b(k) = (10*4^k-4)/3 which is the solution of b(k) = 4*b(k-1)+4 with b(0) = 2. %C A075876 The only terms <= 2*10^7 that are not of that form are 0 and 4. (End) %Y A075876 Cf. A075825. %K A075876 nonn,more %O A075876 1,2 %A A075876 _John W. Layman_, Oct 16 2002 %E A075876 a(10)-a(14) from _Robert Israel_, Nov 08 2016 %E A075876 a(15)-a(16) from _Sean A. Irvine_, Mar 11 2025