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 A254335 #13 Mar 12 2015 18:37:59
%S A254335 1,5,25,205,1025,5205,42025,214205,1483025,9023205,45124025,346032205,
%T A254335 1850165025,13411241205,75057010025,391445050205,3161345251025,
%U A254335 16210847055205,121454355292025,648483937264205,3404031807133025,25020163036073205,141141223300374025,1105826524503082205,5545214234515415025
%N A254335 Powers of 5 in base 60, concatenating the decimal values of the sexagesimal digits.
%C A254335 Each sexagesimal digit appears as a pair of decimal digits as on a digital clock. Any leading zeros are truncated. Thus decimal 125 appears as "205" and not "0205".
%H A254335 Michael De Vlieger, <a href="/A254335/b254335.txt">Table of n, a(n) for n = 0..1200</a>
%F A254335 a(n) = A055643(A000351(n)). - _Michel Marcus_, Mar 02 2015
%e A254335 a(4) = 1025, since 5^4 = 625 = 10 * 60^1 + 25, thus 10:25 in clock-like notation, which becomes 1025 when restricted to numeric characters.
%t A254335 f[n_] := FromDigits@ StringJoin[If[# < 10, StringJoin["0", ToString[#]],
%t A254335 ToString[#]] & /@ IntegerDigits[5^n, 60]]; Table[f@ i, {i, 0, 24}] (* _Michael De Vlieger_, Jan 28 2015 *)
%o A254335 (PARI) a(n) = subst(Pol(digits(5^n, 60)), x, 100); \\ _Michel Marcus_, Feb 22 2015
%Y A254335 Cf. A000351 (Powers of 5), A055643 (Babylonian numbers).
%Y A254335 Cf. Sexagesimal representations: A250073 (Powers of 2), A254334 (Powers of 3), A254336 (Powers of 10).
%K A254335 nonn,base
%O A254335 0,2
%A A254335 _Michael De Vlieger_, Jan 28 2015