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 A129450 #7 Sep 08 2022 08:45:30 %S A129450 121,21952,343,484,5625,676,79507,8242408,9409 %N A129450 a(n) = smallest perfect power that begins and ends with digit n, 1 <= n <= 9; one-digit numbers are excluded. %e A129450 a(8) = 202^3 = 8242408; there is no smaller perfect power that begins and ends with digit 8. %o A129450 (Magma) PP:=[1] cat [ n: n in [2..9000000] | IsPower(n) ]; firstlast:=function(x); for n:=1 to #PP do k:=Intseq(PP[n], 10); if #k gt 1 and k[1] eq x and k[ #k] eq x then return PP[n]; end if; end for; return -1; end function; [ firstlast(d): d in [1..9] ]; // _Klaus Brockhaus_, Apr 16 2007 %Y A129450 Cf. A001597 (perfect powers), A075786 (palindromic perfect powers), A128827. %K A129450 nonn,base,fini,full %O A129450 1,1 %A A129450 _J. M. Bergot_, Apr 12 2007 %E A129450 Edited, corrected and extended by _Klaus Brockhaus_, Apr 16 2007