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 A138257 #9 Jul 09 2025 04:28:25
%S A138257 1,1,3,1,7,5,3,2,7,7,6,5,7,13,7,4,5,7,9,7,3,6,10,22,11,7,19,13,15,7,6,
%T A138257 4,31,5,13,7,19,20,7,22,11,13,15,31,7,24,10,69,43,11,5,7,44,19,31,26,
%U A138257 9,15,42,7,31,6,13,4,7,31,69,5,67,13,124,26,9,19,11,20,31,7,18,69,28,11,126
%N A138257 Smallest positive integer m such that n divides [4^m/m] (=A129794(m)).
%C A138257 This sequence is well-defined.
%H A138257 Romanian Master in Mathematics Contest, <a href="https://artofproblemsolving.com/community/c6h187665">Problem 3</a>, Bucharest, 2007.
%t A138257 spi[n_]:=Module[{m=1},While[!Divisible[Floor[4^m/m],n],m++];m]; Array[ spi,90] (* _Harvey P. Dale_, Sep 13 2020 *)
%Y A138257 Cf. A129794, A138255, A138256, A138258, A138259, A138260, A138261, A138262, A138263.
%K A138257 nonn
%O A138257 1,3
%A A138257 _Max Alekseyev_, Mar 09 2008