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 A155584 #13 Mar 01 2023 05:43:32 %S A155584 0,0,1,0,1,2,0,1,3,3,0,1,4,5,4,0,1,5,10,7,5,0,1,6,17,13,9,6,0,1,7,26, %T A155584 21,28,15,7,0,1,8,37,31,65,40,17,8,0,1,9,50,43,126,85,82,21,9,0,1,8, %U A155584 65,57,217,156,257,91,27,10,0,1,8,10,73,344,259,626,273,112,31,11,0,1,8,11,80,513,400,1297,651,325,121,33,12 %N A155584 Array, read by antidiagonals, of n-th strobogrammatic number in base k. %C A155584 If a binary number is palindromic, it is also strobogrammatic. In bases 3 through 7, this is not true, where only digits 0 and 1 can be used, because 8 is not a digit, nor are either of the inversion paid (6,9). I do not show bases beyond 10, although admittedly some letters as digits are other letters upside-down. %e A155584 A[2,4] = 5 because 4th strobogrammatic number base 2 = 101 = 5 (base 10). A[9,8] = 154 because 8th strobogrammatic number base 9 = 181 = 154 (base 10). The array begins: =================================================================================== %e A155584 ..n.|.1.|.2.|.3.|..4.|..5.|...6.|...7.|....8.|....9.|...10.|...11.|....12.| %e A155584 =================================================================================== %e A155584 k=1.|.0.|.1.|.2.|..3.|..4.|...5.|...6.|....7.|....8.|....9.|...10.|....11.| %e A155584 k=2.|.0.|.1.|.3.|..5.|..7.|...9.|..15.|...17.|...21.|...27.|...31.|....33.|A006995 %e A155584 k=3.|.0.|.1.|.4.|.10.|.13.|..28.|..40.|...82.|...91.|..112.|..121.|...244.| %e A155584 k=4.|.0.|.1.|.5.|.17.|.21.|..65.|..85.|..257.|..273.|..325.|..341.|..1025.| %e A155584 k=5.|.0.|.1.|.6.|.26.|.31.|.126.|.156.|..626.|..651.|..756.|..781.|..3126.| %e A155584 k=6.|.0.|.1.|.7.|.37.|.43.|.217.|.259.|.1297.|.1333.|.1519.|.1555.|..7777.| %e A155584 k=7.|.0.|.1.|.8.|.50.|.57.|.344.|.400.|.2402.|.2451.|.2752.|.2801.|.16808.| %e A155584 k=8.|.0.|.1.|.9.|.65.|.73.|.513.|.585.|.4097.|.4161.|.4617.|.4681.|.32769.| %e A155584 k=9.|.0.|.1.|.8.|.10.|.80.|..82.|..91.|..154.|..656.|..665.|..728.|...730.| %e A155584 k=10|.0.|.1.|.8.|.11.|.69.|..88.|..96.|..101.|..111.|..181.|..609.|...619.|A000787 %e A155584 =================================================================================== %p A155584 strobo := proc(b,n) %p A155584 option remember; %p A155584 local a; %p A155584 if n <=2 then %p A155584 return n-1 ; %p A155584 elif b = 1 then %p A155584 return n-1 ; %p A155584 else %p A155584 for a from procname(b,n-1)+1 do %p A155584 isstrobo := true ; %p A155584 dgsa := convert(a,base,b) ; %p A155584 for d from 1 to nops(dgsa) do %p A155584 if op(d,dgsa)=1 and op(-d,dgsa) <> 1 then %p A155584 isstrobo := false; %p A155584 elif op(d,dgsa)=8 and op(-d,dgsa) <> 8 then %p A155584 isstrobo := false; %p A155584 elif op(d,dgsa)=6 and op(-d,dgsa) <> 9 then %p A155584 isstrobo := false; %p A155584 elif op(d,dgsa)=9 and op(-d,dgsa) <> 6 then %p A155584 isstrobo := false; %p A155584 elif op(d,dgsa)=0 and op(-d,dgsa) <> 0 then %p A155584 isstrobo := false; %p A155584 elif op(d,dgsa) in { 2,3,4,5,7} then %p A155584 isstrobo := false; %p A155584 end if; %p A155584 end do; %p A155584 if isstrobo then %p A155584 return a; %p A155584 end if; %p A155584 end do: %p A155584 end if; %p A155584 end proc: # _R. J. Mathar_, Sep 30 2011 %Y A155584 Cf. A006995, A000787, A006072, A068188, A007597. %K A155584 base,easy,nonn,tabl %O A155584 1,6 %A A155584 _Jonathan Vos Post_, Jan 24 2009