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 A303500 #74 Jul 03 2021 07:58:58 %S A303500 2,21,210,2101,21011,210110,2101100,21011000,210110001,2101100011, %T A303500 21011000110,210110001101,2101100011010,21011000110100, %U A303500 210110001101001,2101100011010011,21011000110100110,210110001101001101 %N A303500 The smallest positive even integer that can be written with n digits in base 3/2. %C A303500 a(n) is a prefix of a(n+1). %C A303500 The smallest, not necessarily even, integer in base 3/2 with n digits is a(n-1) with 0 added at the end. %H A303500 B. Chen, R. Chen, J. Guo, S. Lee et al., <a href="http://arxiv.org/abs/1808.04304">On Base 3/2 and its Sequences</a>, arXiv:1808.04304 [math.NT], 2018. %F A303500 a(n) = A024629(A305498(n)). - _R. J. Mathar_, Jun 25 2018 %e A303500 The number 5 in base 3/2 is 22, and the number 6 is 210. Therefore, 210 is the smallest even integer with 3 digits in base 3/2. %p A303500 roll32 := proc(L) %p A303500 local piv,L1 ; %p A303500 piv := 1; %p A303500 L1 := subsop(piv=op(piv,L)+1,L) ; %p A303500 while op(piv,L1) >= 3 do %p A303500 L1 := [seq(0,i=1..piv), op(piv+1,L1)+1, seq(op(i,L1),i=piv+2..nops(L1))] ; %p A303500 piv := piv+1 ; %p A303500 end do: %p A303500 L1 ; %p A303500 end proc: %p A303500 from32 := proc(L) %p A303500 add( op(i,L)*(3/2)^(i-1),i=1..nops(L)) ; %p A303500 end proc: %p A303500 A303500 := proc(n) %p A303500 local dgs ; %p A303500 dgs := [seq(0,i=1..n-1),1] ; %p A303500 while not type(from32(dgs),'even') do %p A303500 dgs := roll32(dgs) ; %p A303500 end do: %p A303500 dgs := ListTools[Reverse](dgs) ; %p A303500 digcatL(%) ; %p A303500 end proc: # _R. J. Mathar_, Jun 25 2018 %Y A303500 See A024629 for the base-3/2 expansion of n. %Y A303500 Cf. also A304024, A304025, A070885, A304272, A081848, A246435, A005428, A073941. %K A303500 nonn,base %O A303500 0,1 %A A303500 _Tanya Khovanova_ and PRIMES STEP Senior group, May 09 2018